I'm excited, but it seems like setting names by default is very odd. Quite a bit of the PEP is dedicated to the odd situations created by "case x" actually setting x rather than reading x ("case .x" would read x). Wouldn't this be a natural place for := ? So you would do:

  case x := _

to match and assign to x. "_" would always be the matcher. You always have access to the original item that the match was made on, so pulling out the matched items is often not needed, AFAICT. This would be explicit, and not too surprising. Then the whole dotted names part can be dropped - it works like normal Python at that point.

The PEP already suggests this for capturing parts of the match, why not just use it for all saved matches? It's more verbose, but consistent, with fewer caveats, and not always needed.

Disclaimer: My languages don't happen to include one with good pattern matching, so I'm not strongly familiar with it.