The only way they can do the whole "tanks just tank" meta is by making optimizing your abilities, including dps ones, apart of keeping aggro and reducing damage. No one except lazy tanks or people who don't even play tank want to just use the basic system we have in place for those things.

As I've mentioned before, it'll only work if there are some big job changes almost on the level of warrior back in 2.1 as well as changing the mechanics of bosses and enemies which just won't happen.