Tevez has consistently maintained that he will leave Juventus at the end of next season to return to Boca Juniors. If Falcao is willing to take a pay cut (and obviously depending on what happens during this summer) I can imagine him ending up at Juventus.
It's a shame because I would happily have Tevez here. He's a right little bar steward, but like Cristiano Ronaldo, he seems much less detestable from a distance.
Regarding Falcao's next club, I suppose for the most part it is a matter of who could afford him (and who would want him). I can't imagine anyone in the Premier League will be interested (with the possible exception of Man City, although that would probably depend on one of their current strikers - likely Dzeko or Jovetic, assuming Negredo doesn't return - leaving), but a move to PSG doesn't seem entirely unrealistic, nor one to Real Madrid who aren't exactly saturated on the striker front (assuming they don't take on Hernandez permanently). I suppose an outside bet might be the MLS or Russia, but I don't think Falcao is quite that close to finished just yet.