Debating a "transitional" Python 2.8

I kind of like the idea of a "Python 2.8" which is produced from a Python 3 source tree, is compatible with 2.7, has 2.x semantics (unmarked string constants are bytes, not unicode), but insists on more portable usage.

For example, it could still recognize the print statement by default, but consider it deprecated or illegal. If you want to use "print" you need "from __future__ import print_function;" and to use it as a function, but it also doesn't just start handling things the new way. Likewise, it understands ambiguous "except" clauses the 2.x way, not the 3.x way, but it prohibits it.

Personally, I think the biggest impediment to Python 3 adoption is that it lacks support for "unicode" and the "u'foo'" syntax. Other than that, it would be possible to have a 2.8 that makes you write version-agnostic code, but there's no way to get Python-3 strings that also works in 2.7 for 2.8 to demand.