[gregoriol]

There is show and there is reality: French TGV achieved 574,8 km/h in 2007 for show, but it was under specific conditions, not in real world conditions.

While it is technically proven that it is possible to do 400+km/h on rail, it's not practical: maintenance, wear, noise, turns, embranchement, and overall cost, ... many considerations that are probably less important for Chinese railway now, which needs some "show".

[litbear2022]

You should update your data; in 2013, China's high-speed rail reached 605 km/h on experimental lines. The CR450 is scheduled to enter commercial service in 2026.

[whinvik]

Sorry if I wasn't clear but was not talking about demo runs. There are plenty of those. Was more meaning operational speeds having a limit.