I have reasons to believe that Dan Slott will still be on ASM because he still has three important story plotlines to complete:
The Anna Maria Hollogram story arc
The Alchemex story arc
The Black Cat story arc
Yep. I do not see Nick Lowe changing anything relating to Dan Slott's run on ASM. Afterall, when an Editor says that he's a fan of Dan Slott, you know that he'll do everything to make the writers satisfied. The only way that I will believe that Slott's leaving is when we see the return of Doc Ock; The Kingpin, and Norman Osborn......
And for that matter, the return of Myphisto....