On the issue of airfares vs. Amtrak fares: It varies based on the route, the time of year, etc. For a "cheap" air market, Amtrak will tend to be more expensive; for an "expensive" air market, Amtrak will come in cheaper.
As to the number of lie-flat seats...how do you come up with 40, just out of curiosity? Is this assuming 10 rows of 4? 14 rows of 3 (well, 42, but close enough for government work)? Etc.
It is 10 rows of 4 or 12 rows of 3.
BTW I don't know of any airline that is installing any new angled sleeper seats. It's time has come and gone. They are generally all getting replaced by full lie flat seats.
As I said in my previous message., IMHO the angled lie flats are horribly uncomfortable and I consider the Superliner seats or even the old Sleepy Hollow seats better than the angled lie flats, having experienced each of them many many times.
I agree with George that bringing back the old Sections would work well too, and would have about the same capacity per car as the lie-flat seats, and the berths would be much wider in that case. Since the number of seats would be the same as for lie-flat seats the fares should be about the same too, about 60% to 70% more than Coach.
However, if you want to use lie-flat seats, this is the sort of thing you want
However, as George says, the most preferable is the old Sections. And yes, 3 high will carry as many as in Coach quite easily though I find them a bit claustrophobic.