Yep, whoever is closest to the mob has hate. "The trinity" still exists, however, everyone shares all three roles equally rather than one person performing one role at a time. For example, with sword/sword on my Mesmer, I have 5 effective block/invulnerability skills available, each with a fairly long cool-down. Whenever they're available, I 'dodge toward' the enemy to use them, and when they're recharging, I jump back out.
If everyone does this, anything should be relatively easy... *foreboding ellipsis*