Considering that for most of the city pairs, the time savings is minimal yet the fares are much higher, I would think that many corporate travel managers might wise up and make their people ride the Regionals. The Regionals do seem to be filled with business travelers if you ride the trains at the time that business travelers usually ride. Thise who are really price sensitive take the Bolt Bus or equivalent.Which is still at least a year or so away.The more 160 MPH segments on the NEC go into service
I honestly don't know if Amtrak has plans to up the speed with the current equipment either. And on top of that the only additional location where speed will increase is in NJ. The stretch in Maryland and Delaware will remain at the current speeds. And I don't know if their are plans to upgrade the Catenary and Signals to 562 in that area.
Let's remember that Acela is aimed at Business travelers looking to save time. Regional trains are aimed at travelers looking for the best price and are concerned about price.
Now Acela first class is a superior product, and I can see business big shots who don't have to answer to the corporate travel managers spending the extra money to keep away from the riffraff, get a meal and enjoy the open bar.