The biggest question is to first determine what shape & style AW wants to play & if Coquelin as DM best suits that purpose, or if he can be as effective in another position.
IMO Coqulein isn't so much indispensable as DM but more so as the only recognised ball winner, and he could perhaps be even more integral as CM ball winner ahead of a DLP and next to a B2B type pressing high in the opposition half.
IMO it is the lack of an effective ball winner that has been the biggest issue in our midfield. I don't agree with playing 2 playmakers in the midfield in a pyramid shape unless you sacrifice the B2B player for an effective ball winner. As such IMO the best balance & flexibility is with a DLP behind a Ball Winner to press & B2B to provide movement, with one of the Ball Winner or B2B providing some bite/physical power.