> With modern signals and a good track, high speed trains can deliver good throughput with high comfort.

This exists in France where some countryside TGV stations have become Parisian commute towns.

E.g. Angers-Paris (296km, 1h15 by TGV) - http://www.lepoint.fr/villes/tgv-boulot-saint-laud-25-10-201... (French)