Honestly, what I'm hoping will happen in 4.0 is to completely redesign the concept of EX roulette to be more like Guildheist.

Lets say in 4.0 we're level 70. Instead of our current set up, just put all level 70 dungeons in the 70 roulette. Then turn the EX roulette into a more mission based run. They would take the existing dungeons, limit it to a short run but with an objective. Protect and individual, quickly retrieve an item and escape, solve a series of puzzles, hold an wave off; something that could spice the usual run up a bit. Its also a easy way to reuse the hell out of assets in the game already.