While your ideas have merit Tibike, there are large operational differences between airlines and trains that make general solutions somewhat problematic.
I'm not up on airline regulations, procedures or financial limitations. However, I assume that there is no cost to maintain the main piece of infrastructure an airplane uses...and that is the sky. While I'm sure there are designated flight paths and there me be fees to utilize them, I'm willing to bet there is no maintenance fee. I doubt planes are charged by the "wing" or the "number of engines". I'm willing to bet there isn't a charge based upon how fast the plane intends to travel in the flight path since I doubt there is someone in the sky, inspecting the flight path. That means there is unlikely a federal guideline indicating something similar to "This is Class III sky, so if a plane wants to exceed 200mph or use a jet engine, this flight path must be inspected weekly, clouds must be cleared and no plane with a propeller that doesn't maintain 199mph may use the flight path...if there is plane that exceeds 200mph within 10,000 feet vertical feet...unless there are passing sidings that are 40 miles long."
These ARE limitations that exist on train travel. It is quite easy to say "let's maximize frequency between certain pairs," until the hosts get involved. Some railroads charge by
axle! Therefore, running more trains ramps up more access fees. Some railroads charge by the number of trains. Some railroads charge by the car. Some charge by the tonnage. Some railroads may use different charges on different routes. That makes a general solution problematic because there isn't a "general route" or "general fee" that exists. Trains have to follow the track and the owner of the track sets the bar and can assign fees. The bottom line is you can't assume that running more trains won;t DRAMATICALLY increase your contribution and nullify the revenue.
A perfect example is the second Pennsylvanian. That is coveted, state supported service that Pennsylvania desires. At one point, there were two trains. When the restoration of a second train was proposed, NS stated they wanted millions in infrastructure repairs, new sidings, new tracks, upgrades to the signal system, etc. CSX wanted almost a billion in infrastructure repairs to restore a train on a previous route that is still operation.
The large elephant in the room is PTC and who will assume the costs. This is where you might have hit the nail on the head Tibike. There are hosts that have basically said, if you want to use this route, you'll have to foot the costs of PTC. If in fact Amtrak did foot those costs, then they need bang for their buck. Running as many trains over their territory is a wise investment. However, what if the costs of the investment doesn't translate into ridership and/or revenue? Should you make the investment merely to keep "the system" together?
Well, that is the ultimate question and that once again boils down to, finances, revenue, ridership and politics. What is more important...revenue or ridership? I'm not from the west cost Tibike, so I'm going to need your help. Using the Coast Starlight as an example, you have stated that running it as separate corridor trains may stimulate ridership since the train is not helpful to people in CA. Am I understanding you correctly? If that is the case, it would make sense that the top city pairs for this train would be long distance passengers since this train isn't reliable for corridor service. Again, this makes sense. Now, the REVENUE from the LD pairs is going to be quite higher since typically, the greater the distance, the higher the fare. So, taking a train like the CS and breaking it into various trains may increase ridership but you'd have to hope the volume makes up for the potential loss in revenue from the long distance trip and the potential increase in fees. What if it doesn't?
A classic example is the Capitol Punishment....I mean errr Limited. On its own, this is dopey train. It has poor arrival times at the main city along the route (PGH) and poor connections (relatively short in one direction and too long in the other direction.) The intermediate markets are small and poorly served. However, if you attempt to change their schedules, NS has basically promised to paralyze the train....not that it should matter since they kind of do that anyway, so what harm is there in changing the times?
However, from a system perspective, this train is a major west-south conduit. It funnels a great deal of through traffic between the east coast and the mid west. Altering the train would impact the entire system. So, if a host wants to pass the PTC costs along, a cursory look would suggest you kill this train because as a stand alone route, the finances of the city pair wouldn't justify the investment . However, an in depth look would make you have the opposite point of view. That is because the through ridership is there and with that comes revenue not only for the route, but for the system.
Speaking of the system, that is where politics comes into play. I know things are different now, but there are plenty of people that don't believe in trains. Period. If you want them, pay for them! That sounds logical but there are plenty of people that will not vote for funding a scattered system. In other words, it sounds good to say you're going to invest BILLIONS in the NEC....until someone in Kentucky says "Sure, as long as you continue to stop in Mayville!' and someone in Montana says "I'll allocate for a national system, which means Malta. So if you think you're turning the Empire Builder into two trains between CHI-MSP along with one SEA-SPK train, you've have another thing coming!"
The trains are shorter now then they have ever been. However, I think that is because of slightly better utilization and assignment. That may also be because revenue (higher fares) are trumping ridership numbers (lowering fares may drive up the numbers but may not translate into revenue.). Additionally, shorter trains traveling shorter distances doesn't necessarily mean less maintenance or less head count. Quite often, it means just the opposite. Short distance intercity trains must have a calendar day inspection lust like a Long Distance train ,except a long distance train can actually continue to its final repair point if a non-running gear defect is found en route. That is not the case for commuter or short distance intercity trains. Additionally, a delayed en route LD train can continue in service to its next calendar day inspection point. That is not the case with SD/COM trains. They can continue to the next inspection point, but not with the passengers. Multiple trains may need additional crews and crew bases. Again, this MAY not be an issue. It depends on the costs, the ridership and the revenue.
These are all major issues, Tibike. Where trains exist, I believe in multiple services. You already have the stations. You already have the mechanical forces available. You already have the crew base and commissary profile. If more trains can utilize them, that's better. So, I'm not saying your idea for breaking up the CS may not be a good idea. However, will the states fund it? If they kill the train, does that mean other states will fund what is left? Will Oregon willingly fork over money to invest in the NEC? Our new CEO may believe so but I really don't think that is the case. We could lose it all.
We may find out soon enough. My prediction is a push to corridor type trains, financed by the states. We may not have a choice. If that fails, you'll see a nod to sustaining the system by running a perfunctory train with minimal amenities and a puny consist. The rest of the equipment will be diverted to other places in the system to feed corridor type service. Again, this may NOT be the end of the world, depending on how it is accomplished.