i think stalkers actually look kinda interesting from what little i've seen so far. rogues in wow and most other games just initiate fights from stealth and then have some more or less long cd to also stealth in fight every once in a while.
stalkers look more like the thieves of gw2, who go invisible for just a few seconds at most, but very frequently even while fighting, sort of 'dancing' around the enemy and combo-ing different cc, burst and stealth-hit effects together. it's obviously hard to tell how much fun that will be without actually playing it, but i do love thief and hope stalker gameplay will go in a similar direction.
as for tanking, i wouldn't mind playing a tank that focuses more on actively evading stuff rather than mitigating or absorbing, if they will all be considered about equally useful and viable in terms of balance.