>>45216124At this point the Pokemon being back or not really depends on what they do
If they move onto gen 9 then yeah, likely the cuts will become a permanent thing with no takebacks
But if they make another gen 8 game that happens to add all the Pokemon not on SwoShi then it's likely they might add those missing Pokemon to SwoShi (What with the assets already being done and keeping compatibility between both releases for battling/trading)
The ORAS/XY split over the Megas would be nothing compared to the complexity of keeping the audience so clearly separated to two different games of the same generation