For me I'd like to see "raids" in the sense that groups of people tackle a stronghold or even better a more instanced open world area, but without the narrow definitions of tank/healer/dps. Obviously some people will be able to provide more damage, higher armour, crowd control (explosives, etc.), or better healing options, but I think if they can foster multiple ways for a group of 5 or 10 players to tackle a situation based on the synergy between each other's skills, it could lead to a pretty interesting experience. The key being that everyone brings their own skills to the situation and has to focus on their own survival as well as each others.
As another enhancement, instead of being mostly indoor corridor-style dungeons, the "raids" are really more open world (instanced) zones, including buildings, that a group has to overcome various challenges to reach some objective. They could have progressing stories as you achieve different results (perhaps even allowing some variance on what happens in a given "raid").