I think a Kasich/Rubio ticket could compete in PA, but it would be tough.
I actually still think Trump won't be the nominee. Come vote time when people close the curtain, I think the "poles" aren't really as accurate as some think.
As more of the low-level guys drop out, those votes for traditional candidates will start to coalesce.
Rubio is starting to make hay. And despite my worries I still think Cruz has a good shot. As Bush, Huckabee, Fiorina, Christie and Paul drop out, I think it tightens up to a 25%-25%-25%-25% battle between Trump - Carson - Rubio - Cruz. I wish Kasich would be in that mix, but I don't see it but he's getting my vote regardless.
Carson is really hitting home with the religious right. Not sure why, but his soft, pious voice is working. I thought he'd have faded away by now, but he's not.
But as this field drops to 4 or 5, it really gets interesting. I've never seen a primary this close among that many candidates before.