On very few select tracks – the Shinkansen could drive 500 km/h, but is still limited to 320 because of a lack of suitable high-speed tracks. Same goes for the TGV, and the Germans don't even bother with trains faster than 250 km/h.
Speaking of which, Germany sold their maglev technology to Japan and China in the first place because there was nowhere to put it at all. With Germany's winding railroad network it's impossible to reach speeds high enough to justify maglev.
400 km/h sustained, over tracks longer than 400km, would already be a massive improvement over the status quo.
Assuming, of course, the Hyperloop will be able to build a sufficient rail/tube network.