I don't think either of those guys would actually make the top of the ticket as I don't see them able to win the primary.
1) Kasich is too willing to compromise. The conservative establishment is not remotely fond of him. He supports issues that are non-starters for the conservative movement, like the Iran deal, Obamacare, Medicaid expansion. He's also not hawkish when it comes to foreign policy, which is a criteria for winning this primary. He's a good man, and I think he might even make for a good President; but it's hard to think he'd be beholden to special interests given his track record.
2) Rubio. Under what scenario does Rubio come out ahead? I just don't see Republican voters nominating him as he doesn't really command a room, and he's never really been that popular among the national electorate.
He's very much like a poor man's Boobie.. I mean, a poor man's Paul Ryan. Republican strategists make the mistake that Rubio has a chance to win or even improve his standings with Latinos - simply by virtue of being Latino. It's the same silly argument for Ben Carson. It was the same silly argument for Paul Ryan; that he could somehow improve Romney's standing with evangelicals and Catholics who might feel he worshiped the devil.
Latinos aren't going to rally behind Rubio, and rather than flocking to the party, they're leaving it in droves. He has no political base outside of the Cuban community. That works in Florida, but not on a national stage.
Rubio would be a great VP pick, as would Kasich. But I still expect Bush to win the nomination, and I highly doubt Bush would pick Rubio as his running mate.
Bush/Kasich makes all the sense in the world. As would a that'd be their best shot from an electoral standpoint.