Developing / helping contribute to PyPy may mean touching 2.7 in its toolchain which is used to implement it, but no, users using it have been able to use 3.x for a very very long time now.
You'll note I said I was playing with RPython, not PyPy. In my case, I was playing with writing a small interpreter, and comparing the RPython toolchain with the Truffle/Graal framework.
Writing RPython code, even if one is not developing or contributing to PyPy, means writing within a subset of python 2.
> RPython ("Restricted Python") is a subset of Python 2
... so getting the RPython toolchain (even if one is intending to improve the PyPy 3+ interpreters) requires setting up a pypy 2 interpreter. Hence the question in my post.
