Holy @#$@, people. Did I wake up in a naïveté vortex?
No, C doesn't define sizeof(int). It is implementation defined. But you don't change it once you implement it in a given development environment... not if you want people to create and maintain production code with your tools. You don't speculate that one day you might want to change sizeof(int). It's just not something you do if you want to be taken seriously.
Is anyone in this thread over the age of 16?