For the first two months:

Level 10-50: No change in general, maybe DPS will have to wait a bit longer.

Level 50-60: 45 - 120 minutes of wait time for DPS, Healers and Tanks will have instant queue or wait 1-5 minutes maximum.

Level 60-70: DPS will wait around 20-45 minutes, Healers will wait around 5-15 minutes and Tanks will get instant queue.

After two months, most players will either go back to their previous main (this will affect the queue alot) or they will like the new DPS classes and stick with it, which means less Healers and Tanks.