I hope pictures will go into our sims inventories with proms and other events

If it doesn't, I would hope we could at least edit the prom location (even if it's with cheats) so that we can set up the photo booth from either Moschino Stuff or Get to Work.

University already gives you a degree and a little picture of your sim in their graduation robe iirc, so that's probably going to be a recycled asset for the High School graduations. I'd be more worried about whether we get little prom mementos like we did in Sims 3 or not.