I think there will be two separate films : The first film being a Spiderman 3 with multiple baddies including Electro, and a Separate Spiderverse- multiverse film which may bring back Maguire, Garfield, and other actors from the franchises past.
I think those two options are very possible at least on Sony's end.
If there's one thing fandom should have learned from this year, its to never say never when Hollywood is concerned.
No one on these boards, or in fandom would have thought Michael Keaton would be returning as Batman nor Foxx returning to the Spiderman franchise, only half of fandom thought there would be a Snyder cut released in the near future, less fans then that thought Ben Affleck would return as Batman, and no one ever dreamed that Grant Gustin and Ezra Miller's Flash's would interact on a tv show.
Alot of fans may be ahead of themselves on the future of Spiderman on film, but at this point, its more folly to say something isn't possible, than to say something is possible.
This is a new era, and studios are beginning to think outside the box as far as approaching these films.