You're underselling Jacare. He has big power in his right hand at least and has good timing with it. Also, he has major strength, and good td's with a judo background.
I wouldn't pick anybody against Weidman. He has power and technical ability to win on the feet. He can take you to the ground with pretty good proficiency. And has nasty gnp and solid bjj once he gets you there. But where he's kind of unproven is in the transitions and from his back. He's never been on his back before, and only Maia, who had a huge size disadvantage and was gassy, tried to put him there even once. I'd be interested to see what Jacare could do with his strength + judo + world class bjj, and if he could land that right hand solidly a few times. He's the biggest threat, and a serious one, IMO.
Romero is in a similar boat as Jacare, if he pulls off that upset. Although he's frustrating in the way he won't change his pacing. Weidman may just be too quick for him.
Weidman comfortably beat Machida the first time, but Machida may have learned he just needs to open up more than usual if he wants a realistic chance to beat the Chris. He was coming on at the end of the last fight when he made that realization.
Of course Belfort has a good chance to land a big kick from safe distance for at least the first couple of rounds. Then it should be heavily Weidman's world in the likely event he makes it past that point.
A bunch of guys in this division full of killers toward the top have a very realistic shot, but all will be deserved dogs.