It also becomes harder to build a working compiler for anything other than Linux
Now, it is even less possible. I like to bring up DOS as an example that can't even fit the paradigm of the C++11 specification. How on earth are you going to have threads in DOS?
This can be done with user space threads
You also have the long long int type, where if you need to use that on a 32bit system, it will need emulated
long long int existed as for quite some time, gcc and msvc support in on 32 bit platforms.