Jeb is finished.
The Establishment is going to make him step down because they know Florida is the big one. They need as many Rubio supporters as possible.
If Rubio loses Florida, then the Establishment is going to have a tough time winning after he loses in his home state. This is where he is still an active Senator.
I suspect Jeb’s supporters will go to Rubio.
However, Florida is already solid Trump.