Whilst fans would like to see Lewis paired with Verstappen, Vettel, Alonso, Ricciardo and even Button, I would expect Toto would now prefer to have Lewis paired with a good No2 driver for several reasons. It's often been claimed that the last 3 years of Mercedes domination has been killing F1, therefore, having Lewis paired with any of those drivers above would be more than likely to extend the period of Mercedes dominance producing a continuation of 1st and 2nd positions in races, especially if Toto's rules of engagement are enforced, whereas all the same drivers competing for different teams does not include "rules of engagement", so clashes between the drivers are more likely.
Many fans claim that the Mercedes car is so far ahead of the rest that any of the top 10 drivers could've achieved what Lewis and Rosberg have done, so if that's true, then Toto could get the likes of Hulkenburg, Bottas or Perez as a No2 driver and get the same results, without all the difficulties he's had between Lewis and Rosberg, due to them having equal driver status. Likewise, if Wherlein is thought to be good enough, then he should take the seat and he could be coached by Lewis to succeed him.
If Lewis was treated as the Mercedes No1. (as I believe he deserves) then provided Mercedes continues to produce the best car, they would continue to win the WCC and they could also help Lewis to beating Schumacher's record.
Clearly, being a title contender is a "pressure cooker" environment, which has really got to Rosberg to the point that he can't face it any more. So the way that Lewis copes with it is remarkable. The fact that Lewis enjoys doing other things away from F1 between races and keeps turning up and performing, should silence the likes of Keke Rosberg and Jackie Stewart for their criticism that Lewis doesn't show sufficient dedication to being a driver. I think that all work and no play makes Nico a very dull boy has been proven.