I don't agree. Whilst Aguero hasn't been firing yet he's still a few levels above Nacho who often has a poor touch and makes wrong decisions. He's also shown he's capable of a sublime touch and made some great choices of pass so not worried.I'm not as brave as you and wouldn't go quite as far, but there is no doubt Nacho can offer THE TEAM a lot more than Kun. It'll be a while until Nacho is a clinical as Kun.
His time will come.