All indications are that we'll see 3.10 before 4 is considered.

I think it would probably be ok to start thinking about it in a year or two from the py2 sunset. It will be a minor update anyway, it's just a PR exercise that can be done whenever people think it would be more effective.

New features planned for python 4.0:

http://charlesleifer.com/blog/new-features-planned-for-pytho...

You missed a /s there.

I dont think python 4 will be what you think it will. Most likely it will just be the next version of 3, not a game changing upgrade.