Paladins are already viable. Classic brings in some TBC crap balancing that screws up some items for us but overall we are viable as Rets.
Just don’t expect to top dps meters, you are not a class supposed to do that, you are supposed to be a supportive dps that can do stuff other than filling that pretty pink bar.
Unless the talked timeskip brings them a chance to work on another game with a different graphic engine that keeps the level of world immersion of WoW, there is no reason not to keep going with expansion over expansion of the same things.