It is literally happening right now. The people who have demanded that everybody switch to python3 instead of simply forking python have proven the FUD true.
If you want forks there are forks. Off the top of my head, Redhat is supporting Python 2 for several more years and there's a project called Tauthon [1] that is "Python 2.8" in spirit. I'm sure there's more efforts I'm not aware of.