I don't think Carlsen will want to have Kasparov as second, I doubt he is the type of guy to create the right mood for Carlsen. Vallejo has title match second experience, and Anand has good Spanish connections. Caruana is maybe too strong to work as second, but Anand was seen talking quite a lot to him at the Tal Memorial. Giri is another possibility.
As for Carlsen, I could imagine him going for some lower rated player he knows well, like Hammer, rather than top players. He worked a little bit with So in the past, so maybe that is another option, or some other young player like McShane or Vachier-Lagrave?
Does anyone have the latest scoop of Anand's seconds or Carlsen's seconds?
So far the knowledge that I have is that Anand will have Surya Sekhar Ganguly as a second, and will definitely not have Nielsen, Rustam or Wojtasek.
Regarding Carlsen, it is known that Kasparov offered help, not sure if Carlsen accepted it?
Please share the latest rumors here...