Honestly, if Cain can get through Overeem and maybe one or two more guys (Werdum, not sure who else), I think Bones would be a really interesting fight.
Jones has very solid cardio--5 rounds with Rashad and 4 with Rampage and didn't appear tired in either fight. Cain might wear him down, but Jones probably has better cardio than any current HW besides Cain. (Cormier and Barnett also had good 5-round cardio, but Cormier won't fight Cain and Barnett isn't even in the UFC yet).
If Jones can defend TDs relatively well and fight decently off his back (he has the long limbs to be Anderson Silva-ish), it could be really interesting. Cain's pressure vs. Jones reach and unpredictability. If Sonnen were somewhat larger (say a 6'3" 245 pound natural HW), he might gives Jones the same challenge that Cain would, but I don't think the actual MW/LHW Sonnen will be able to work his pressure game.
If Jones gained 10-15lbs in muscle, I think Jones would be favored. He'd still have a significant reach advantage over Cain, and a 3 inch height advantage. He'd essentially be able to fight him like he did Shogun, or even would fight Dan Henderson. Just keep him on the outside, pepper him with shots, and punish with knees/elbows from the clinch if Cain decided to get close.
mr. Bones barely could take down Rampage, let alone mr. Rashad. How is he going to take down Mr. Cain? His best shot is to run for 25 minutes doing his little knee kicks and front kicks (which is the most cowardly move ever).
I don't know what the betting lines would be but it seems that every time a fighter looks like a rangy, unsolvable puzzle like Jones does now, the answer has always seemed to be pressure as was the case for Machida, JDS, Erick Silva, Anderson Silva(even though he beat Sonnen) so we'd have to see someone jump all over Jones to find out if that would throw him off.