> Despite decades of development, only a handful of routes in Europe operate at anything like airplane-competitive speeds, which for all but the shortest routes, require > 300 km/h or > 185 mph.

Not really, given massive fixed cost at airplane terminal and airports being typically harder to get to than train station.

When I was flying this summer, I was asked to come to airport 150 minutes before planned departure.

200 km/h train would still be faster for distances of about 700 km.

And even for longer routes benefits of comfort, larger possible baggage, lower stress and so on would make it a clear winner.