Currently you can get around this with Panama, even if the API is kind of verbose for the purpose.

Eventually value classes might close the gap, finally available as EA.

Valhalla is over 10 years in the works already and there is still no clear date when or if at all it would be released. It's very difficult to change (or fix) such fundamental things so late in the game.

Because it is a huge engineering effort to add value types without breaking existing binary libraries.

Doing a Python 3 would mean no one wanted going to adopt it.

Yes it is long process.

Some of the JEP in the last versions are the initial baby steps for integration.