Mark Waid: for all his other virtues and flaws, very possibly the actual last guy in the world who would be inclined to screw up Superman's costume again.
Were he to be on the main book, my one wish is the same with him as with anyone else: have the first issue be a grand, multiverse-spanning quest to travel back in time to undo the Bendis run in its entirety, only for it to fail spectacularly and end with the entire cast facing the fourth wall and declaring "welp, I guess everybody's gonna have to continue dealing with this cool setup being how things work now. AH WELL". Far more likely though is a big Black Label Superman project from him: he's a hardcore "Superman is defined in large part by his loneliness, the Superman/Clark divide and love-triangle-of-two dynamic with Lois is sacrosanct" partisan, so while he's I believe mentioned liking Bendis's run in an AMA I don't see him playing nice with the current status quo for long-term work, and I imagine he'd want his potential final go at the character as the starting shot of his big return to DC to be something more than a standard Action Comics #1029-1050 anyway. Specifically, I think he's going to do something akin to Spider-Man: Life Story with Clark, for the following reasons:
* That's big enough to be
"the one Superman story (he's) got in (his) back pocket" after Birthright and Kingdom Come - everything in the middle, essentially.
* While it could work as a standalone Elseworlds-ey thing if it didn't fit however the plans ultimately turn out or the winds simply changed, DC could use exactly that right now for figuring out Superman's place and how he and his supporting cast work in the new 5G history, which we saw in Superman #25 has already at least somewhat gone into effect for him (this being a method that would mercifully not require another full-on origin retelling).
* Most significantly: Waid's made very clear he's been doing a lot of research for his not-official-but-let's-be-real Superman book, and...well,
he's Mark Waid. If
HE needs to do research for a Superman project, it's something going absurdly in-depth in terms of the history of the character.
So I could easily see his big thing being him and let's say Jim Cheung doing 4-6 issues going "here's Clark as Superboy in the 1950s - or Golden Age Superman in the 1930s depending on DC's mood this week - here's the emotional behind-the-scenes of his 60s and 70s adventures, here's Death and Return and the marriage and Jon and all that, here's how Lois and Lana and Ma and Pa and Jimmy and Perry and Lex are all alive in the 2020s as Superman embarks on exciting new adventures". Fits his desire to make his stamp and contribute to Superman in a big way, fits DC's current setup, gets you a high-concept big perennial no matter how things turned out long-term. I'm not saying I'd bet the farm on it, but that's how the pieces line up most logically for me. And if he did an ongoing run after that the way he's made clear he also wants, he'd have carved out a whole new space for classic-model adventures to tell stories with his ideal take in.