The guy is a fringe-elite offensive talent from the blueline, but I don't see how any franchise can or should get past some of his off-ice extracurriculars (which, to some extent, seem to bleed onto his on-ice product).
In many ways this reminds me of the Curt Schilling situation in Boston/the MLB (if you'll forgive me taking this to another sport for a moment)... guy was clearly a HOF player and an all-time Sox hero but if the stuff about him that's come out in his post playing career years came out while he was active - I don't think I could ever root for him or support any team he was on - and that would probably extend to a sizable chunk of fans.
There's reasonable debate as to the depth of TDA's issues/concerns - and whether they go as far off the deep end in his present iteration as Schilling's, now - but an team willing to cope with the potential headache is probably going to ask for a 25-50% AAV reduction baked into his deal. Attacking D of his age are usually making around $100k-125k per point on their deals. If he were a less worrisome signing, that equates to a AAV somewhere between $5.5-7m... but given his history, my guess is he lands somewhere between $4.5-5.5 depending on term.