The Fleet Strategy Plan is a mess. No real way around that...it's focused on fleet replacement rather than even secular growth, from what I can tell, and it doesn't seriously discuss shorter-term demand needs, let alone propose solutions to them (even piggybacking on some sort of commuter car order to deal with capacity issues on the NEC, for example).
Edit: To explain: Vis-a-vis FY03, Amtrak had about one million more passengers on the LD trains and 2.2 million more on the NE Regionals directly...and another 800,000 down in VA that got "split off" later. They had a million more on the Acelas. Though the presence of the Metroliners and the Clockers muddles things a little bit here, there wasn't a big shift between '05 and '06, when both brands were dropped.
So, between the Regionals, the LD trains, and the Acelas, Amtrak added a million passengers, and was able to at most augment the Regionals with a couple of Clocker/Metroliner car reassignments while the LD trains have gotten bupkis. Even the "short corridors" haven't gotten new cars since the California Car order back around 2001. Mind you, there was room for load factor improvement there, but it's hard to keep growing when you're incessantly constrained on the capacity front, and I'd point out as well that the IL/MI/MO/CA order can't help out back east.
Right now, IMHO, Amtrak should be looking for funds for 100-200 new single-level coaches over the next few years, in addition to another round of sleepers and diners (to allow at least some shifting of routes to single-level from bilevel trains, allowing those cars to be cascaded onto the Western LD trains). It doesn't matter so much where they're aimed; if they're LD coaches, it would allow some Amfleets to be moved from LD service to either long corridor service (with seat rearrangements) or NEC service; if they're corridor-aimed coaches, you could arguably cascade Amfleets (again, with seat rearrangements) the other way.
The point is that Amtrak is beginning to push capacity limits in a lot of places. We're looking at ten-car Regionals; do we have the equipment for eleven or twelve car Regionals in a few years? Can we add another million riders per year on the NEC? If so, where are the limits on current equipment? If ridership grows at 2%/yr, we'll be at nine million riders by FY18; at 3% we'll be there by FY16. Adding in Virginia trains, those targets for nine million become targets for ten million instead. On the Acelas, the load factor is even more dire...from what I see, we're approaching 75% of theoretical capacity in some months (that is, assuming each seat can be used once south of NYP and once north of NYP; I noted that we were close to this bar one November), which suggests a certain amount of full-to-capacity trains near rush hours.
Edit: Straightened out borked code.