Create a new difficulty level for all the content that will never be made Epic - Level 20.
I would suggest that only quests that were originally level 14 and below that were never made epic would be eligible.
I've discovered that being able to run the epic content on epic normal actually greatly improves my enjoyment of the game - I'm running old quests for optionals, kills, breakables, and looking forward to opening chests.
Wouldn't it be cool if all the old quests that people only run for favor could be ramped up to level 20? You could run the quests as something more than a zerg, and it would hugely expand where you can get your high level xp. Instead of running Impossible Demands 30 times after cap, you could run Sorrowdusk with a group and enjoy it again!
The possibility of upgraded level 20 versions of end chain rewards is not the point, but I do think the idea of someone running around in L20v Asbestos Booties is hilarious.
I just want to be able to run old stuff for favor and still get some xp out of it. I would suggest that running at Level 20 would give the same favor as Elite, and that you could only run on Level 20 once your character WAS level 20.
Before you ask, No, I'm not asking for new epic loot. I can't think it wouldn't be easy to level 20 the mobs on most of the content. With Epic Normal as a standard, most mobs have a high level alt already. Also, I wouldn't have these quests drop token fragments on end chests, but mobs with CR over 20 should drop them in Treasure Bags.
Thoughts?