The age of emulators will most likely end at the GC/PS2 generation, or the Wii I suppose but its just an enhanced GC so a lot of the work was already done in Dolphin. The complexity of PS3/Xbox and future consoles will make it almost impossible to create an emulator. The amount of processing power required just doesn't exist, and won't exist for a long while. On top of that, the new systems will most likely require a network connection to have the best user experience. This by itself will be difficult to reverse engineer since you would have to understand both the server and client side of things.
Now, I'm not saying it impossible, but you would have to have the man power and hardware knowledge of Microsoft, Sony, or Nintendo to build anything close to useable. Even then, emulators made by the big boys still have lots of bugs and issues. But alas, there is literally NO reason for them to do this.
I feel confident in saying this: They will NEVER exist or be attempted.