@Fizz Enthusiast: What is Riot's vision of an assassin?

Just a quick question: What Riot believes assassins should be doing post 6.22?

Previously, assassins were supposed to get to a target, quickly take them out, and leave the fight. Some would give up the quick exit for other stuff, like dueling power and vision control , or for extra tankyness , or sometimes a semi global engage . But nonetheless, they'd do one thing EASILY: kill their squishy target. This was obviously not a fun situation to be on the other side of (as you mentioned in your Clunkiness and Fun post), and changes to it were expected for a reasonably long time.

Right now, assassins seem to be in a weird conceptual spot. They are not supposed to be GRANTED the kill, even if they execute it properly, as enemies have a bigger windows for counterplaying them. In the late game (or in general team fights and coordinated skirmishes), this usually means that unless the support and tanks/peelers have wasted most, if not all, of their CDs, as well as the target having wasted their defensive options, the assassin will probably not get the kill or not get out of the fight alive. Sometimes they fail in both aspescts.

This would seem to lead to a more snowball oriented playstyle, specially with the changes to Zed and Rengar, who get more damage after getting kills, and Talon and Leblanc, who were given roaming tools. However, the Armor-Pen-into-Lethality changes, seem to indicate a more late game oriented approach, specially with Lethality being such a huge part of AD Assassins items.

Those 2 aspects, at least for me, seem to leave Assassins as a class without a clear indentity or goal, mostly due to how contraditory those two things are: late game they are easy to counter, but they only get the full power from their items in the late game.

So, to put it shortly: what are they supposed to be doing?