More of a right sided attacker than a pure winger, and he's probably going to extend his contract with Dortmund (right now, he's 'focusing on the Armenian national team' - apparently), but with just 1 season remaining on the current deal, maybe Raiola can be convinced to agree to an Ibrahimović ++ double whammy.
A lot of fantasy transfer formations are starved of genuine creativity, with an overload of goalscorers - vying for the statistics - which can be an unsustainable model to build upon. Just think that the emphasis should instead be on bringing in atleast one top provider - so to speak, who can look up, and seek out passes to better positioned team-mates (more often than not), instead of always going on goal himself.
With the way we might be lining up next season, Zlatan + Martial (who will hopefully take the next step in his evolution) should be the primary goalscoring tandem for the team, with other creative influences feeding those two - and there are very few superior creative threats around these days than Mkhitaryan - who worked beautifully with Aubameyang and co. this season - like, comparable to Müller + Lewandowski level good (though Mkhitaryan is probably the most underrated of the lot). Has quality defensive workrate - and Mourinho generally prefers to have slightly imbalanced flanks to provide a sounder defensive structure off the ball. He can be that, in contrast with the more tactically free left flank.
One of the most important things our attack is missing right now is a 'brain' (eg. the true point forward in an LVG system - who can be the intelligent operator in the attack) - and Mkhitaryan has been exactly that over the past season. And he's in his prime too, so should be able to hit the ground running - and maybe sustain that level for 4-5 seasons.