Do you have an idea already how stealth in LoL could work that isnt already discarded ? Last time Xyph seemed a bit desperate that long duration steath just doesn't work.
Essentially, stealth makes you 100% invisible, but imagine all champions have Oracle's. What this does is makes it so your engagement range and such are the same, but you can scout, use it strategically or set up good positioning with it. Obviously, kits would be adjusted to utilize this.
I'm not 100% sold on this currently, but it's definitely the best-testing solution we've had. It's a tough problem in a game where information has such a premium.