I have no doubt that the plot thread of the identity reveal is going to plan a big part of the plot regardless of whether its a multiverse film, or a Spiderman 3, sans the multiverse.
I don't think the identity and multiverse threads have to be, or will be, mutually exclusive.
As far as getting Maguire and Garfield back for a multiverse film specifically , Yes .
It makes sense from a story telling, marketing, GA, fan, and a business perspective, if you're doing a multiverse film.
Now ,what capacity they could be in the film, if they go that route, remains to be seen.