Both Kotka and Poehling are 100% centers to me. I'd move Domi to the wing before ever thinking about anything else. Same goes for the prospects really, I'd move Suzuki and Evans to the wing to keep them at center in a minute. You don't mess with natural 2 way centers.
Domi is a 70 point center, our first in many years. If you no longer want that, just trade him for a great return. Why people would think of moving him back to wing where he has to engage in board battles instead of owning the middle of the ice is beyond me.
Poehling is another Danault, a late first round pick with some offence, though he didn't exactly light up the NCAA.
However, if you play Poehling in a power forward role, he will possibly excel, due to his willingness to fight for pucks, go to the net and get deflections. I think it's worth a try.
On the other hand, if you prefer Poehling as a C, you don't have to trade or muzzle Domi, you can also trade Danault. It might be preferable if Phil is going to cost $5M on his next contract, and Poehling can fill his shoes.
Even if you think Poehling could be a number two C, I'll say what others have said about Danault: it's even better to have a 2nd-line capable C as your third center if you want to compete for a Cup.
In two years:
Drouin-Domi-Shaw
Poehling-Kotkaniemi-Caufield
Tatar-Danault-Gallagher
Lehkonen/Byron-Suzuki-Armia
Trade Byron or Lehkonen in the meantime for defensive help