I think a Champions series and Dr. Strange 3 would be the perfect projects in-between Doomsday and Secret Wars
The Champions series is reportedly already in early pre-production with Rachna Fruchbom set to be the showrunner, while there has been chatter of a 3rd Dr. Strange movie being planned to come out right before or right after Doomsday as early as 2022.
With the rumors that Spidey and Dr. Strange won't be in Doomsday, at least not in a significant role in the story, and Spidey getting his own solo movie right before Doomsday, it only feels right for Strange to get his own third outing between Doomsday and Secret Wars.
Ideally, it would take place at the same time as Doomsday and deal with him and Clea stopping Incursions, similar to Strange's arc with the Black Priests in the Time Runs Out event, which seems to be what Doomsday will be based on anyway. I imagine a similar situation to that of Ant-Man in Infinity War and Endgame. He was not in the first movie, but his solo sequel came out right after IW, took place roughly at the same time as IW, and most importantly set up some pretty important plot devices for Endgame.
Of course, for the movie to come out in that July 2027 slot, it would need to start filming in July 2026 at the very latest, which means it needs to have a writer and director on board already or find one by next month.
Some will say that the July 2027 date will just be scrapped like all the rest and is being held out just in case, but I seriously believe they have a plan and that's why they didn't scrap it during the latest slate update.
Some others will say that Black Panther 3 or X-Men will premiere on that slate since they are the only movies to be confirmed to be deep into pre-production, but we already know BP3 still has a way to go, because Ryan will do the X-Files reboot first. Plus, rumors already want BP3 to take the February 2028 slate to coincide with the 10 year release of the first movie. Similarly, X-Men will most likely take the May 2028 slate to coincide with the MCU's 20th birthday and usher the new Saga and a whole new era of the MCU.
That doesn't leave us with many options for that July 2027 slate, unless you think Blade will reenter production.
As for Champions, Wanda is also rumored to not be in Doomsday, but with the set up they have in place right now surrounding her character, it's the perfect time to adapt Children's Crusade.
Let's look at everything they have laid out for this story:
1. Wanda is gone and presumed dead by most 2. Her kids have just been reincarnated as different people, are realising who they really are and we can assume they will soon start to look for her 3. Dr. Doom is now "in the game" 4. Wanda's powers and the prophecy of the Scarlet Witch being the one to either save or destroy the Multiverse fit really, really well with the Multiverse Saga and could be utilised to bring it to a satisfying close 5. The Young Avengers/Champions are starting to form
It's either now or never.
And considering these characters seem like they will have slim to non-existent roles in Doomsday, it'd be perfect to do another Ant-Man and the Wasp and have Champions show come out between the 2 Avengers movies, but take place during Doomsday, featuring the kids trying to find Wanda in order to save the Multiverse.
Now I know that they've said they want to separate the series from the movies in terms of plot significance in order to attract more casual viewers and not make them feel like they need to do homework to watch their films.
But the show could have no significant consequence to the plot of Doomsday, so viewers who watch it will only have an enhanced experience and see the whole picture of what's happening, but those who don't, won't miss plot points which will damage their experience. Kinda like Clone Wars in Star Wars.
They could also use this show to conclude Riri's side plot with Mephisto, who could be the villain of the show, using Riri to manipulate the rest and eventually try to strike a deal with the twins and offer Wanda in return. Considering Billy's darker nature that was set up in Agatha All Along, this would be a natural progression of the story which would tie up a lot of loose ends together and give closure to some stuff set up in this Saga, which we would otherwise wait for the next Saga to see any continuation of.
I had made a post last year trying to predict the plot of Doomsday using all the different set ups and loose ends and Children's Crusade as well as Dr. Strange's arc during Time Runs Out were part of that plot, but now I see they might not be essential moving parts to the core story they're telling in Doomsday. But they will make for great side-pieces, filling in the gaps and setting up stuff for Secret Wars, which is why I believe they absolutely NEED to do these projects before the Saga ends.
Black Panther 3, X-Men (confirmed, in pre-production), Blade, Shang-Chi 2, Strange Academy, Nova (confirmed, on hold for now), Midnight Suns, Annihilators, Thor 5 (rumored, early development) and whatever they plan to do with Eternals can happen in the next Saga and it will still make narrative sense, even though most of that stuff was set up in this Saga. But without these 2 projects and these 2 stories they need to explore, I truly feel like the Saga's ending won't be as fulfilling as it could be.