Let Kassadin's Q shield scale off of his targets AP as opposed to his own
Basically it seems like Kassadin is shifting from a bursty assassin playstyle to a more hypermobile mana bruiser style whose specialty is being able to quickly reposition in teamfights as opposed to blowing up a single target. Also helps cement him as more of an antimage (he'd make a nice counter to the ap tops we've started to see more and more often).
WHERE IS YOUR AP/MAGIC DAMAGE NOW!?