As this piece points out, if Jeb runs, Sen. Marco Rubio almost certainly won't. I predicted shortly after the election that the Republican Establishment will lock in on Jeb Bush as their favorite for 2016. They are certain this election was all about the Hispanic vote and they're convinced Jeb is the man to win it over.
Whether Republicans are ready for another Bush is a fair question, but the Establishment sure is. I suspect they say Rubio too much of a gamble, the way they did Paul Ryan. This would be another Blue Blood candidate in the Mitt Romney mold. If Jeb being in keeps Rubio out, I would oppose his candidacy on those grounds alone.
This piece also points out that Jeb might not want it. I'm convinced the Establishment wants him. They see him as Hispanic friendly and they're convinced that's the voting bloc that cost them the White House in 2012. I think that's incredibly small minded. There is an excellent field of potential candidates for 2016: Rubio, Ryan, Bobby Jindal and yes, possibly, Scott Walker. To lock in a a candidate with a toxic last name over one demographic is the kind of myopia that has been killing the Republican party