Train is very suitable for the overnight travel ; there is probably a market share for that on the cross country lines like NY-LA ; getting into the train in the evening, reaching destination in the morning, which is more enjoyable than the 6 hours long flight which ends up eating a whole day anyway. Long range high speed train hasn't yet been really set up in Europe, but its time might come in the US.

HST and what you call Express lines are thoroughly codependent. In France for example, smaller cities not far from the high-speed corridor do get direct trips along the corridor : eg see Paris and Lyons, two big cities 600km away, first HST line in France ; Grenoble is about 100km from Lyons, and has direct lines to Paris. i.e. all cities 'close to the corridor, even if they are not large enough to get a the new lines built to the city itself, are in effect part of the corridor.  Very important in getting more politicians on board :)

(You wouldn't believe how much was done to get the TGV in some places ; Les Sables d'Olonnes, a seaside resort, has no electrified railway. So for the end of the trip the TGV train is pulled by a diesel...)

Oh, and about train speed, a new high speed record is coming on a railway east of Paris at the beginning of april. Probably over 300mph.

Un roi sans divertissement est un homme plein de misères