The thing is, whilst we do have a fair number of central midfielders on the payroll, many of them are consistent underperformers who are wildly overpaid. Provided we could bring in better replacements, I suspect most of us would be content to see three of Davies, Delph, Gomes and Sigurdsson depart - look at the rage levels on here whenever one of those is named to start in the middle (not Delph, obviously. If he were named to start, most of us would faint and the club's medical staff would be arrested on suspicion of witchcraft).
The proof of the fact that only Allan and Doucoure are suitable for Prem-level competition is that the very moment we lose one of them, we start to struggle, to the point that we have to alter the way we play and change our shape. When BOTH of them are missing, we lose. This isn't to say that the other positions you mention aren't needed BUT in the ongoing attempt to trim the wage bill (and thereby facilitate the purchase of better players) I bet the club will be looking to shift another big earner out... the only part of the squad where we can still do that is in CM.
I think another midfielder is absolutely vital, unless Gbamin somehow turns out to be the answer. At the moment the third midfield space is just rotated between a number of underwhelming options, it's a massive weak spot in the team. I agree that we need a wide player and a centre forward but at least we've currently got good players there, that starting midfield spot needs a big upgrade.
@Lanolin, I agree it's a weakness - a glaring weakness.
The issue however is if you consider we've already brought in Allen and Doucouré; with the deficiencies elsewhere, it may not be top of the club's list.
Simply, we can't start next season with Coleman, and for all the great work others have done there it limits our offensive capabilities down the right.
Nor we can start next season with Iwobi as our primary option on the right or with only DCL and Richarlison; King may resolve one aspect, but we'll see.
Those two or three areas there should vastly improve how we play and for me the focus should always be on first improving the XI rather than the squad.
While the midfield is a concern, my point is/was that I expect any movement there will be dependent on moving on one of Gylfi or Gomes before we move.
That should be a priority too as your points are completely valid, but as others have said we could have James move there if other places are filled.
So for me, RB and RW > CF > CM in that order. Resolve all of that and we'd be in a much, much better position.