In my opinion (not backed up by any rumor mill sources that have said anything), I'd expect Imagination to get work first if Inside Out is truly heading in the Magic Eye. I do think the two will go down for work
close to each other (around 18 months apart when it happens) but Imagination will be first, to ride in on the IO2 hype (which does sound insane considering Disney drags their feet to cash in on new popular films, but consider the fact this is a billion dollar maker and is about to beat Incredibles 2 for highest grossing Pixar film, which would likely push a quicker timeline maybe? but we still don't have the DLR avengers e-ticket... but they could easily animate the ME film while working on the planned shorts(?).)
But as I've stated before, technically neither are officially greenlit and don't expect anything at D23 and for all I know the Inside Out stuff could fall apart.
Also while I'm here, I've seen people on other places speculate Frozen in Epcot will get actual faces and not projections and I haven't heard that at all, sorry