>>36772571here's what I honestly think they will do.
They didn't take out secret bases or contests in ORAS so I don't think they will do that with the underground or contests in Sinnoh, the underground would stay cause they'll push the 'playing with friends' aspect of it, something co-op as well.
Dressing up Pokemon in contests tho, I think they will make it certain only for certain pokemon, i.e Pikachu and Eevee -_-' but not all pokemon, it would be too much work on the models for lazyfreak to do.
BF is obviously gonna go cause 'muh kids and phone games' excuse.
The house, def will be replaced.
I don't see why they would change the rivals team roster, it's fine as is.
Mythical events will obviously just become event codes.
They'll use the "It's a Diamond/Pearl remake! not Platinum!" excuse to ditch Pluto and Distortion world, though I think the DW would become and episode thing.