Agree with why Jose made sense as an appointment - for exactly the reasons you mention.
I think where I differ from you is the 'keep us in top 4' part of your post.
I don't see us finishing top 4 this season. Question is whether its realistic to expect the players which we bring in this summer to lead us to top 4 next season.
Depending on your view on that (which comes down to how far off we are, how much we have to spend etc) probably leads you to different answers on (i) who would replace Jose if he leaves and (ii) the type of player which you sign this summer.
I agree we won't go for unknowns, but I'm not sure I see us going for the type of manager who Chelsea often hire - Conte, Ancelotti, Hiddink, Benitez, Grant, Scolari,...