Well, they do have a nerve net of sorts, but the way they achieve immortality they more like regress back to "baby" form and grow back, so it's more like they just become their own baby.

In theory immortality is possible, yes, consider this, every single cell you are comes from the same cell every other known living thing comes, LUCA, in a way we just are just LUCA witch some changes that means that as far as we know cell division is unlimited.

So as long as we can prevent or fix any change or mutation and recode any natural oversight in our cells that prevents immortality it should be achievable as far as we know.

Anywho, it would be achievable on our biological body's.

Also where is the fun in stopping, we aren't made to stop exploring.