Which classes will be the best to challenge content higher that the level bracket, say above level 30?

Thinking that it would be a fun challenge to see how far it is possible to push the level 25 bracket, I was beginning to think about what classes will be performing well and not in those fights.

Will physical dps be able to hit their targets and will casters only see Resists on their spells? Will tanks need to build massive health pools or focus on avoidance instead?

What classes or even party compositions do you think will be strong in challenging higher level instances or level 30+ elite quests?