I'd need to check how long the validation lasts, since it may be well be like emulated PS1 games from the PSN ("PSOne Classics") and Steam's offline mode, both that take a few years to reset, but neither permanent.

It would depend on the launcher. Considering that cracked launchers do exist which just bypass this step entirely, I'm sure there are plenty which only really check once just to be on the legal side of the law. Third party launchers are a thing - there is nothing stopping the application from just running the game. I don't think it would even be possible to permit third party launchers and somehow have the game break itself after a set period of time without internet connection, except for maybe an EULA which they would just have to be trusted to follow. And the EULA doesn't mention third party launchers.

Cracking also isn't really illegal in a lot of jurisdictions if you already own a licence for the game. But you wouldn't even need to crack it for Minecraft anyway.