It's Unsworth's to lose now. He has been clear in saying he wants the job permanently and at least BK seems to be minded to give it to him, reading between the lines. This most certainly does not seem to be the normal caretaker scenario, though I hope the club are still looking at all options in any case.
FM may need convincing, but if Unsworth does well, surely its his.
I think he will get longer than 4 games, he may get 6-8 weeks before any sort of decision is taken. He could go on in a temporary capacity really until the end of the season though I imagine if he is still in the job by December, they will want to clarify his position for the benefit of everyone, either to confirm he remains in place until May or offer him a longer contract.
It's because I think he will get longer than 4 games, that I think Dyche/Allardyce will come into play then if poor form continues beyond the next few games. If, for example we don't win any of our next 4 league games, then thats a third of the season gone with 2 wins. Worst case scenario obviously but I think at that point the focus shifts more to looking over our shoulders and sorting problems, unfortunately.