I don’t see commuter rail speeds increasing much in the US. If the LIRR, Metro North, and Jersey Transit could have effective speeds (i.e. station to station) of even 60 miles an hour it would be a game changer for the US’ largest and most economically important metro area.
Alas, that’s a pipe dream, much less bringing New Haven or Philadelphia into the reasonable commuting radius which is what I suspect you are alluding to.
I'm a West-Coaster so am not sure why that would be so impossible a task. What stops us in the Bay Area is heavy diesel trains and lots of stops with no passing tracks, and I understand we're working on fixing all of those issues, slowly though we may progress.
Alas, that’s a pipe dream, much less bringing New Haven or Philadelphia into the reasonable commuting radius which is what I suspect you are alluding to.