I read the article as saying it ignores all upper-bounds, and 4.0 is just an example. I could be wrong though - it seems ambiguous to me.

But if we accept that it currently ignores any upper-bounds checks greater than v3, that's interesting. Does that imply that once Python 4 is available, uv will slow down due to needing to actually run those checks?

Are there any plans to actually make a 4.0 ever? I remember hearing a few years ago that after the transition to 3.0, the core devs kind of didn't want to repeat that mess ever again.

That said, even if it does happen, I highly doubt that is the main part of the speed up compared to pip.