The biggest issue people have with python3 is unicode support. Unlike python2 python3 puts a clear distinction between characters and bytes. It also is quite strict about it.
The problem with 2.x scripts is that they mix characters with bytes quite often. This is not something that you can easily fix by a program, because from this perspective 2.x programs are broken and need to be fixed.
What you are suggesting is already available, python 2.x and 3.x can be installed and work side by side without any issues. There's even 3-to-2 conversion tool (converting backward is much easier than the other way since python3 is more strict).
The problem really comes down to distribution maintainers, for example we are talking about Guido extending support from 2015 to 2020 for Python 2.7. So before this announcement, Python 2.7 would no longer be supported in 2015, yet we have geniuses at RedHat still shipping it with Python2.6.
And no, there is no incompatibilities between 2.6 -> 2.7 as there's from 2.x to 3.x
The problem with 2.x scripts is that they mix characters with bytes quite often. This is not something that you can easily fix by a program, because from this perspective 2.x programs are broken and need to be fixed.
What you are suggesting is already available, python 2.x and 3.x can be installed and work side by side without any issues. There's even 3-to-2 conversion tool (converting backward is much easier than the other way since python3 is more strict).
The problem really comes down to distribution maintainers, for example we are talking about Guido extending support from 2015 to 2020 for Python 2.7. So before this announcement, Python 2.7 would no longer be supported in 2015, yet we have geniuses at RedHat still shipping it with Python2.6.
And no, there is no incompatibilities between 2.6 -> 2.7 as there's from 2.x to 3.x