This seems weird to me. Won't this cause a fork in Python at some point, where the 2.7 developers continue on 2.8 or rename it entirely, and another fork continues on what is now Python 3?
Python 2.7 hasn't has any improvements since python 3 began, and it won't. All this announcment means is that Python 2.7 will continue to get security/support for another 5 years.
Who knows where 3.x will be in 6 years, but now a huge number of people will continue to develop in the 2.x series with no worries. Six years feels like a long time when you're at the beginning of them. By the end, maybe it will be easier to just tweak the Python 2.x codebase than switch everything to 3.x.