Patience!
Let's not all jump the Gunn here (sorry David). :unsure:
The timetables, as seen by surfing the Amtrak reservations website and putting in certain dates and scenario's, are not final. I watch them all the time, and typically they change up to the week before they are to go into effect.
Regarding this particular situation, there is no way that #449 and #145/147 (147 is the train's number on weekends) are going to operate that close. One will inevitably delay the other, no matter which runs first.
Look for one of the following to happen:
#449 and #145/147 switch places. This would put #145/147 in a later slot on the NEC from New Haven to Washington, but it would maintain through service over the Inland Route from Framingham & Worcester to points south. Under this scenario #145/147 would also switch slots with another train, probably one of the 400-series shuttles between Springfield and New Haven. So yes, one would be able to take #449, and with a reasonable wait, transfer to another train at SPG to go south.
Another possibility is the annullment of #145/147 and its northbound counterparts 140/142 east of Springfield, keeping them as just Springfield-Washington trains like the other 14x-series. I am not sure what the passenger counts have been at Framingham & Worcester on these trains, but it can't be all that much. For intra-Massachusetts passengers east of Worcester, there is increased service on MBTA commuter trains, which operates more frequently and is cheaper anyhow.
Finally, there's still a possibility of extended Silver Service to Boston. While this has not been discussed lately with the moratorium on new trains and the abandonment of the Network Growth Strategy, the intent was to extend one Silver Service train to Boston, over the Inland Route so that mail/express could be handled at the mail center in Springfield. One main reason this was shot down, particularly for the preferred extension of #98 beyond New York to Boston, is that it would meet with interference with commuter trains between Worcester and Boston. Plus, the passenger-unfriendly CSX, which owns the tracks between Springfield and Boston, does not want any more movements on its tracks, so to run, say 97/98 or 91/92 over the route, the existing Inland Route train would have to go. I would venture to guess that extending a Silver Service train to Boston, over tracks already used by various existing Amtrak trains, does not constitute a "new train".
Again let's see what ultimately happens come the end of this month.