What Role Should Assassins Play?
As Riot is trying to help assassins, I have to wonder what they what the champions of that class to do, both for themselves and their team, and how to make that fun for everyone.
What do you want them to do?
Personally, I want assassins to have a higher kill threat during the early game, access high priority targets during the mid-game, and both snowball and fall-off harder than mages do. I think that the kill-threat, target access, and snowball are the most fun parts about the class but also the ones that will need almost constant attention from Riot because they can leave fed assassins as the only ones having fun.
All have?
R,
W/R,
R,
W,
E) that you need, then the bare minimum of CC, then as much damage from ADCs/mages/assassins as possible that you can fit into one team, because nothing else can compete with it. They simply get melted by the damage before they can do anything meaningful, and the block abilities negate the other teams attempt at catches, if used properly.

has most of its value in hp rather than ad and only does damage because of its over tuned passive that also buffs adc damage like they need it) tank items