I think it depends on 2 things really. Firstly if Fonseca has said yes and will give them the nod. If not on how we finish the season. If we win 3 games, particularly the derby, finish top half etc I can see him staying.
I get your point re continuity and stability and generally agree (for example with Hindsight we should never have sacked Koeman) however I just can't see it with Allardyce. Currently 90%+ of fans want him gone on polls, I'm just not sure any managers position is tenable give those numbers. The only thing stopping that contagion spreading is the acceptance from many he will be gone by the summer with continued reports of Fonseca/Brands.
If he is still here, it's hard not to see enormous pressure from game 1 next season and unless a flying start is made, it really spilling over. Potential protests within the stadium but also protests becoming more generalised towards the board and Moshiri. We have a very good window, of the summer to find a new manager, it's very hard mid season (as we found this year) and it would be an enormous mistake to not replace Sam in the summer for me, as it's hard to see us doing anything other than wasting another year on self imposed transition if we don't.
The final point, is that young players, who were meant to be a key pillar of our strategy will be ousted under him. Cookman will leave, and the likes of Dowell, Connolly, Klaassen, will not be given game time.
I agree with you, I don't think it's automatic he goes, but god help us if he doesn't.