zlacker

That's a fair distinction. For the specific case of CC-by-sa 4.0, it's possible to convert to GPLv3. That doesn't help with prior versions of CC-by-sa.

So, for the specific case of material contributed to StackOverflow on or after 2018-05-02, it's possible to use it under GPLv3 (including appropriate attribution), so any project compatible with GPLv3 can copy it with attribution. Any material before that point is not safe to copy.

>>JoshTr+(OP)
It does help with prior versions, since you can use CC BY-SA 3.0 material under CC BY-SA 4.0, which is GPLv3-compatible. (See https://meta.stackexchange.com/a/337742/308065.) It doesn't necessarily help with future versions.

>>wizzwi+Ae
I stand corrected, thank you! I forgot that CC-by-sa included an automatic upgrade clause, unlike many other licenses that require an explicit "or any later version" to do that.