I disagree here. An assassin gets in, gets the job done (then preferably gets out alive).
Old Ahri, even without DFG, could get in, land a charm, finish her combo, get the kill, then use 1-2 remaining charges of her ult (or flash, or simply run, or if only 1 character do nothing) to get out alive.
New Ahri can get in, deal damage, then get out alive. Notice what's missing, the kill. Unless the enemy is already weakened (in which case any tank/bruiser/fighter could also get the job done) Ahri isn't going to be securing the kill (at least not quickly). She'll definitely be capable of chasing until either she gets the kill or gets killed, but more often than not it will be the latter because the carry will deal more damage back. Or she can go in and do 100 - 20 on the carry and get out, but what good is that? Someone else is going to have to go in and finish the job.
Kite-assassins don't work. Theoretically at least. I could be wrong. My thought though is, if she's capable of killing you in a full combo (in order to be an assassin) why in the world would anyone chase her (to let her kite)? If she's kiting you (as a kite-mage) then she can't assassinate you, she can only slowly drain your health until it's too late for you to realize to turn around and run and then she can try to engage (which requires the enemy choosing to fight, an assassin would choose when they fight though not let the enemy decide).
Riot says Zed was a healthy assassin when he's the farthest thing from it. He's an assassin AND a split pusher AND an objective take AND a 1v1 duelist rolled in to one super overpowered champion. Ahri WAS the HEALTHIEST assassin in all of league. She NEEDED to land charm to pull off an assassination (one of the harder to land skillshots in the game), she had lots of counterplay, and she wasn't good for much else other than waveclear and getting picks (again using her charm). She couldn't split push very well, she got dominated by duelists in 1v1 duels if she couldn't burst them 100-0. If they wanted a kite mage, they should have made a new champion, don't change an existing one that some people liked.