I had a thought I want discussed.

As we all know, you upload your brain to a computer and you won't actually be the upload, if your biological body dies and your upload is still there, you'd still be dead, the consciousness doesn't cross over. Therefore, immortality is, for the most part, impossible, because your brain/consciousness cannot be replaced like your organs without you dying, at most you'd have a copy of you alive, but you are dead.

So, is it possible to maintain consciousness and technically still be alive if there was a way to slowly replace one brain cell at a time? I'm talking about a mechanical replacement that keeps the same function but doesn't degrade/rot like your organic flesh would. As if a nanobot had quickly replaced done a switcheroo on one of your cells and you were conscious for it, technically you don't die, but eventually all your cells are mechanical. Because otherwise your brain lasts 200 or so years before dying even if everything else is replaced.

Is this a way to bypass death without losing consciousness, is this possible?