I confess that I too am a bit concerned about epic tier as I've seen the power increase just with paragon tier in my players. The tricks up their sleeves now are pretty impressive and even their healing ability (while lacking a true healer) is amazing.
That being said, Calaystrx did just wipe the floor with them (though they were missing one player). So, maybe there is hope for the future.
I do think that things like increased damage (perhaps even above the MM3 math), terrain-based damage, and action recovery abilities will go a long way toward helping with this issue but I think it will still be difficult to keep the encounters entertaining throughout the entire tier.
Certainly for gods, primordials and even certain demon princes, I think it is more than fair to "break the rules" so to speak in designing them. After all, Lloth, Tiamat, and Orcus are likely not all that interested in a "fair fight".
For those of you who have run extensively in the epic tier, have you found ways to keep the "regular" encounters entertaining? Its one thing to break the rules, or add things like action recovery, to solos, but I think its another issue entirely to do so with standards. Are MM3 damage figures enough to keep standard encounters entertaining? Obviously the idea of ten levels worth of solos isn't exactly appealing.