I think the “can’t let it end”, means they left it open when Laurie types the line “I killed my boogeyman, but evil never dies… it just changes shape.” And there is a reason they used to call Michael Myers, “the shape” in the credits.
If you don’t think a studio would use something simple, as that line, as a springboard to carry something on, then you haven’t watched enough franchise horror films.
Think back to a dead Jason Vorhees, and during his autopsy, the coroner is overcome with evil and eats Jason’s heart, and becomes the new incarnation of Jason. If they choose to carry on, they will find some stupid solution like that, to have the new shape take form.