Turkey recently made its Incirlik Air Base available ..., and has joined in lethal air strikes against ISIS

I think Turkey has managed one sortie against ISIS by now? Everything else was directed squarely at the PKK in a thinly veiled attempt to subvert the general election results.

Stirring up that hornets nest has the potential to draw a direct involvement of NATO. And regardless of what happens in the field, if Erdogan succeeds, NATO ends up with a de facto dictatorship as a member. This has the potential to get a lot uglier than it already is.