Love this idea.Well realistically the devs are not going to produce a lot of quests per year anymore so an end game that is going to be sufficient likely has to revolve around loot and quest repetition. An idea I have for growing the end game is creating a higher quest difficulty then elite for the lower level epics - like say epic quests level 20-25 making a difficulty called nightmare which is approximately the same difficulty as 26(level 20 epic nightmare) through 30 (level 25 epic nightmare) epic elite. That way there is more quest variety for the end game.
The concept that has been floated around on the forums by the devs is a new type of item - that I am guessing is a weapon grind which builds upon itself. The concept was pushed back along with the cap raise to 30 - this is obviously not a coincidence. My guess is you get the base item by running a certain quest or raid and then can get ingredients which build upon the item through a variety of endgame quests. Nice concept overall.
I think that raid timers do not help the end game and hurt the game overall. One thing I dislike about raid timers is they hurt running raids on higher difficulties then normal. If people had to wait 2.5 days to run raids they would think about running higher difficulties to maximize their opportunity to get loot faster. Currently, the most optimum way to get loot is to run raids to 20 completions which is also something that should be re-examined by the way.