FOSS gamedev and creative worlds

You will end up with weird errors. Especially with shared libs that minetest (and other stuff you build) dynamically link to when running.

Edit: by the way, I said not to use a pre-built repository because not all LTS distro have that available! Also, try it on a distro other than ubuntu

Honestly, safest would be to switch only when the main repositories of all major distros' LTS versions point to a g++ version that compiles C++11 without extra options like "-std=c++11". At that point you'll know C++11 is truly mainstream. It might be 10 years from now, but....