This is a complicated question hehe,
GSP: He can out wrestle Anderson in a sailors second, however GSP has a glass jaw and his vision is horrible. I see him wanting to do something fancy rather than his typical pin down and tire out the opponent strategy which in return will land him on his ass and match over. The only chance like I said he has is to pull a Chael and keep him down, but I also dont see Anderson ever allowing anyone to pull that off again.
Chael: He had his chance, he beat him for 4.5 rounds and got stupid, and now he's gonna get spanked by Jon Jones.
Jones: No chance what so ever. He is our modern day GSP but hes not at that level quite yet and that means on his backside
Luke: haha oh lord welcome to the UFC son, enjoy your short lived spot light cause Silva is gonna pop that bulb in an entertaining fashion.
At this moment I don't see anyone that can beat Silva but the closest is GSP. This is why there isn't anyone on the schedule, they have this hope that the super fight between GSP and him will happen but I honestly don't see it happening, I think its great for the fans but bad for the UFC as a hole, someone will get embarassed and it will mildly taint there legacy and overall feel in the said division.
So yeah through this babble, no one at this moment rings a bell that can beat him, but I guess to end this anyone can catch the chin of the champ and finish him off but haha unlese inspector gadget comes in and does it he will enjoy the belt till he retires!!