Honestly I'm not really of the fan of the "Corki is gonna do mostly magic damage" role riot shoehorned him in. AS it is now tanks with one armor and one magic resist item (2 items) are near impenetrable to Corki's damage alone til he has the luxary to afford his penetration (usually void staff) usually as the 4th item AT THE EARLIEST (because he NEEDS the crit/ad/as to make it worth it first). And then at that point this Corki kinda hyperscales, but only because most tanks are used to building 2/3rds armor, 1/3rds magic resist.
Corki's old damage split was actually much more beneficial to him (with his autos doing full physical, +10% true damage, and then his abilities doing substantial magic damage.) It meant no laner could possibly itemize sufficient defenses vs. him to easily turtle up. This lane dominance was something I was used to exploiting mid lane and on rare occasions top lane.
His current setup gave him a hyper late game but the pros abused that and his package endlessly til it was nerfed to where we are now.
Maybe just maybe we should go all the way and make Corki do 100% magic damage? Because this half and half auto is hurting his options itemwise. But maybe it's a terrible idea. Another idea is some kind of ap stat to auto attacker stat scaling.