There's nothing saying that Specter (or any of the others along the Broadway's route) would have to take on Byrd directly. In theory they could have "logrolled" something like "Daily Cardinal requirement (up from 3x weekly) in exchange for requiring a daily Broadway". Of course, that might have just triggered either dropping the Cap and/or converting it into a stub day train WAS-PGH (which would, to be fair, then be a train largely lacking in any real patronage in Washington and likely just get the ax later).
Capitol Limited ridership PGH-WAS is consistently anemic. We know that nearly half the riders are transferring to the Pennsylvanian. Looking at the numbers with overhead removed, I don't see a path to above-the-rail profit -- whereas the Auto Train, all of the Silver Service, the Cardinal, the LSL, and a revived Broadway Limited can all be made break-even before overhead.
Why? On the CL, the intermediate stations contribute basically nothing. (Perhaps this is because MARC runs as far as Martinsburg, meaning that Cumberland and Connellsville are the only unique stations.) The track is super-slow. I doubt that PGH-PHL-WAS (7 1/2 + 1 1/2 = 9 hours) can be made as fast as the Capitol Limited (6 hours), but if Pennsylvania High Speed Rail were ever built from PGH to PHL, the CL would probably be cancelled the week after it opened.
The LSL was originally advertised as a Boston-Chicago train, and has eventually become primarily a NY-Chicago train with a Boston branch. The CL should become a Philadelphia-Chicago train with a DC branch, because that matches the ridership flows.
Edit: I've taken at least some of the fight over the Pennsylvanian to be related to Amtrak's costing (that's a repeated quibble in general, I find...nobody is happy with that and there are quite a few "black box" issues all over that have, I believe, actually been crimping Amtrak's cash flow because Amtrak hasn't been supporting their bills with cost breakdowns.
I think we've all concluded that Amtrak's overhead allocation is gibberish.