The chances of any of these happening are pretty slim, to be honest. The old continuity has been abandoned, so Omniverse shorts will never happen. The only way for us to get a Ben 10,000 series is if he's introduced in the reboot. Also, Generator Rex has been over for some time, and I don't think we'll ever see anything new from that series.
I don't know how long CN can continue to milk Ben 10. The reboot has received overwhelmingly negative reviews from fans and critics and has mediocre ratings. It's probably going to end after two or three seasons.
It's highly unlikely all the above are going to happen.