Depends on what you mean by high speed.
Currently high speed in the US means the speed that the British HST achieved in the early '70s, about 200kph. The airport train in Norway (Drammen to Gardermoen) can do that where the track and traffic allows and runs every 20 minutes.
And you are right about local trains, last time I was in Bonn (about 15 years ago) there was a train leaving the station every two minutes (not to the same destination of course).
Which seems in itself to be a huge problem.
If Hyperloop can dispatch pods at shorter intervals, then high speed transit becomes a lot more user friendly. For the same reasons buses that run every half an hour are not the solution to mass transit, but put buses out that run every 5 or 10 minutes and the usefulness shoots way up.
Well, there's the real problem with Hyperloop. It's not really feasible to operate switches more frequently than 45-second headways, even on conventional rail. Modern approaches generally have a capacity of 30 trains per hour, which means the same approach can service a dozen different routes. In Hyperloop, you would have to build a different approach for each of those routes, which requires duplicating the most expensive part of the infrastructure.