D&DN makes me laugh at times. Signaature spells are more or less encounter powers by any other name and they have already added at wills. They may have 4th ed written all over them but 3.5 had them in the Book of Nine Swords IIRC and 3.5 aso had at wills in the form of reserve feats and Pathfinder has elements of at wills and encounter powers as well even if they are disguised as 3/times per day or XYZ number of rounds per day.
Not saying they need to bring back AEDU across the board but it makes sense for things like the Dragonborn race and it would be a great way to make the races more interesting as well. Elven accuracy for example fits with elves being accurate with bows and it could be applied to magic attacks as well for elven wizards and clerics. Not all races for example need to have a racial power as long as they have something that is relevent for them.
Now this leads to class design. I'm not 100% convinced that the new monk is very good and I do not like that they seem to be adding expertise dice every martial class- fighter, monk and rogue so far. The Warlock would be a good candidate for some encounter powers IMHO. Balance can be important but we all now what is broken from 3.5 and 4th ed and I would like to see some classes designed a bit more like 2nd ed ones. In pre 3rd ed some classes were more or less designed along the lines of "winging it".
I'm starting to loath ED dice. The concept is good but I have concerns it is going to be overused and it ruins the whole bounded accuracy thing in terms of skill checks with skill mastery and mighty exertion. I do not want to see ED dice used on classes like the Ranger, Paladin and maybe Warlord. One could even make encounter powers optional via feats like in 4th ed and Star Wars Saga. If one doesn't want to use them for whatever reason don't take the feat.
The concept of encounter powers is a great one IMHO. 4th ed may have overused them as every class had them and a large part of 4th eds class and role structure was built around AEDU. One doesn't have to bring back AEDU at all but I can see a use for encounter powers replacing XYZ times per day/round abilities from pre 4th ed D&D going back to 1st and 2nd ed class abilities as well.