The idea would be fairly easy to make for trion.
Through the 50-60 zones you gain the equivalent to maxed T1 geared, the new dungeons give you slightly over max T2 gear. At this point you have to go to ID to get T3 raid gear where your progression continues to the new T4 raids.
All dungeons would be mentord down to T1 gear, else your wearing new dungeon gear. Meaning people with T3 gear already will have a challenge also doing the new dungeons and they would have to get the dungeon gear as well to be able to do the dungeons easier/quicker. also to access the new T4 raid you must of got a number of achievement points from each new dungeon.
So this means that people who have T3 gear already can go straight to the T4 raids after completing the dungeon stage. This means there current progress gives them an advantage to overs who didn't do any of the raids before. Where as overs have been given there T1 and T2 gear through questing and dungeons but now must complete ID to get to T4.