"This will be the change that finally kills Tank Ekko!" Says increasingly nervous man for the 11th time this year.
jokes aside, I do think that next patch's changes will finally make AP builds better than tank ones, at least in soloQ. Actually I'd say that they're about even right now, so the changes should kind of be the finishing blow.
I don't think that means AP Ekko will be good, mind you, just slightly better than Tank Ekko. I think he could still use some work, like maybe not having so much of his damage potential be in his ultimate, and I also think that the meta doesn't favor him. When heavy waveclear burst mages aren't as meta, I think AP Ekko will be stronger.
I also think that if the changes to AD Assassin itemization work out well, then Riot should consider making similar items for AP Assassins - AP, flat pen, out of combat movement speed, and some kind of roaming-oriented passives or actives.