Doing the assassin update in preseason Riot may attempt to make stealth healthy.
Stealth has been problematic in league since time immemorial. The root cause is stealth is binary --Either invisible or visible (this leads to the counter play and feast/famine problems). The way to make it not binary is to update vision.
Consider vision to be a misnomer - It should instead be named information. At an abstract level it's purpose is to gain some information to alter the knowledge state of players. Stealth by contrast, is the denial of some knowledge. While this is predominately achieved by vision, there is no need for either to be visual, complete, nor current. By increasing the axes of vision it becomes less binary and thus allows stealth to be less binary. Some may have noticed Riot experiment with this (ward rubble is information, Rek'sai sonar, red-outline of champs). However, these have been limited and can't be applied mid season. More systematic changes to trinkets and wards are needed to allow stealth to work more healthily, but the timing is best for pre season.
My suspicion is rather than change stealth itself, they will modify the vision state to effectively stealthily alter stealth. If stealth is no longer binary Riot are then freed up to alleviate some of the counter-play and feast of famine issues that have wrought havoc.
if Akali stealths you know exactly where she is but you just can't see her which gives her an advantage over her opponent but makes it obvious that she is somewhere near you.
His stealth is attached to his ult and, although he can move around freely, he only has a short window to move around before he is revealed again. This gives him an edge over his opponents with stealth but good enemies can guess where he is going when he uses his ult and capitalize on that information
She cannot choose when she stealths which gives good enemies an advantage against her if they can get her health bar down to blow her passive. You also know the general area where she'll be when she unstealths because the window is so short.
He sends out huge ass blades around himself which gives you a clear indication of where he was when he went into stealth but still gives him the edge of being able to move around freely during the duration.
Has to sit still to stealth unless he's in a bush so you can tell exactly where he's stealthed unless he was already sitting there before you got vision of the area.
Very short window to move around and good enemies can tell when he uses his stealth and capitalize on that information.
