So lets take it as a given that Dos Santos has enough movement, cardio, and takedown defense that no one is going to be able to take him down in the first or 2nd round and that he hits hard enough that after one or two failed takedowns, most opponents do not want to get close enough to try it again, and they let Dos Santos pick them apart. I would still expect that someone with good Kickboxing or Muay Thai would be able to pick away at Dos Santos with leg kicks and teeps, and would have enough striking defense to avoid having their skull caved in. And as athletic as Dos Santos is, he does slow down, it is just that normally his opponent is damaged enough that they slow down more. I am thinking that a viable attack to defeat Dos Santos is the heavyweight version of the Condit vs Diaz fight.
Dos Santos does not necessarily need to start throwing more kicks, but he does need to diversify his attack a bit. Somehow I do not think he is going to be working takedowns into his attacks any time soon.