You are probably the best qualified on this forum to form an opinion - what would you do to get the best out of him?
Thats a tough one to answer - I've been pondering for the last twenty minutes and, accepting that my first reaction* is not going to happen under any conceivable circumstances, even now am not certain of this but...
At the root of the issue seems to me to be that Jonny doesn't feel like he's had a fair shake in the past - whatever anyone here may think, you can see why he may perceive it that way, given how much time he spent as 12th man, thrown in without match prep for ad hoc tests, and constantly the extra wheel in the one day side. He therefore likes the reassurance of having two roles, and has worked incredibly hard to bring his much weaker suit up to a level where this has only been a discussion because of the perception that we need him to bat higher than the gloves allow, and now because we have a "proper" keeper who can hold up his end with the bat.
So, there are a lot of factors here - not least the fact that we have one of the top four a certain pick, and potentially six or seven players who would ideally bat six or seven. His best position for Yorkshire/in first class cricket has been batting at five whilst keeping. That has never really been a feasible bet in international cricket - even Sangakkara was reduced to mortality when he was asked to combine - so the options are combine roles and bat him six or seven, ask him to convert to an opener, or bat him at five (Joe having a sinecure on four). My view? His height means that keeping wicket is going to shorten his career, and Foakes is a definite upgrade with the gloves (and a different type of player in the middle order, which will be valuable going forward), so I would go with a batting only role - and that would be at five long term, with a pitch akin to we want him to be the player KP used to be - play proper innings, but dominate the opposition.
The only problem is who gets dropped!
*if you've read this far and are curious as to the first reaction - it was "give him the captaincy". Obviously not going to happen, but would actually play well with his personality and good understanding of the nuance of the game, lets face it, even if we think Root is improving tactically, the fact is his batting is being affected...