I would be totally down for something like this... But if it happened I'd like high end gear to be easier to get (add an extra two chests to a Savage clear or something) because I wouldn't be able to use 1 tank set for all my tanks.
Right now there's a little funny business and I don't think any role has a single BiS between all it's jobs (for tanks for example warrior wants more skill speed), but it just means have a different piece here or there.
If they're adding more horizontal prog I imagine it would just exacerbate the problem for someone who likes playing a role and don't just have a fav class.