Personally, I'm thinking we'll see War Walkers move from Heavy Support to Fast Attack. I know they aren't speedy but the scout move/outflank means they have a great deal of flexibility for deployment. Besides, they are essentially IG Sentinels with another gun and far fewer wargear options.
The only slot to me that is overcrowded is Heavy Support. I can't remember the last time I took an Eldar army that didn't have 3 heavy support choices (lately it's a night spinner and 2 prisms). Most of the Eldar Fast Attack is lackluster or superfluous given the mobility of the rest of the book. Vypers aren't any faster than Falcons, they just have less firepower and armor. Elites have stiff competition but I rarely fill out elite slots in an army.
Eldar troops need some love though. Avengers are largely the only viable option since defenders you are buying a gun with ablative armor, rangers are too static, storm guardians are okay but only get a single special weapon, and jetbikes are acceptable if you can take a decent number of them... otherwise they are free kill points.
While I'm wishlisting a bit, it would be nice to see a cheap option for transportation. I don't care if it's a webway or an open topped vehicle really, as long as I can get units from point A to B and cost no more than 80-90 points.