Yes - but also more expensive and more comfortable while being geared towards a business class. People aren't completely casualed out on Amtrak - I don't see ripped t-shirts or wifebeaters that I occasionally do see on MetroNorth/LIRR plus it's all carpeted which means grease stains. I felt out of place in shorts when I rode up to Providence a few months ago - there really wouldn't have been room for a full size bike without impeding on those sitting in the front.
just to back this up ... I used to be a fairly frequent passenger on the Acela and Northeast Regional when I worked for a Boston company that had New York and DC clients. The rush hour Amtrak trains are
always packed and it would be impossible to fit a bike on there. I suspect that you'll have space to store a bike during a weekday, non rush hour ride, but I don't think that helps folks who'd like to use the train as an opportunity to take their bikes along on a vacation or weekend getaway.
MBTA commuter rail support for additional bikes only came about after sustained advocacy and support from officials like Menino. I'd like to think that Amtrak is watching the commuter rail bike car program closely and might see that as a barometer of demand for similar services. We shall see.