This formation shouldn't be a problem for him and is not the reason he's playing poorly.
He's not playing wide, just wider than before. This is not like the false 9 of the past. Messi isn't playing exclusively through the middle with two really wide forwards like under Pep. This formation has Messi playing through the middle with plenty of flexibility for the 3 forwards. They're interchanging and covering spaces left by the other.
Suarez moves right into the middle when Messi drops, moves wider out when Messi comes forward, but never asked to hug the wing and take on players there. Same with Dembele in the opposite side with the added duty of dropping deep into midfield to defend and create.
This is the dynamic I saw in the Juve game.
Messi drops: Suarez moves centrally, gives the entire left wing to Alba and Iniesta to operate in space. This has allowed both Alba and Iniesta to play better and combine. The middle is still circulated by Busi, Messi and Rakitic. Dembele can drop and create, or move centrally and receive depending on situation.
Messi moves forward: Suarez moves wider and either receives in the wider area, waits for overlap from Alba and runs into middle, or passes to Messi hanging back in top of box and moves middle. Either way, he isn't being asked to take on players on the wide area. Only shield the ball, pass and move to middle to receive return. Either of those two choices would yield plenty of chances for him receiving return balls. And in fact it yielded several opportunities vs Juve, one that lead to first goal.
In any case, this position should be more than fine for him to thrive, he just so happens to be in poor form for a while now. His poor form was there when he was playing centrally too.