so a machine will probably make a better bitcoin
So if a machine creates an even more powerful or better machine of itself, then how come you would say that it will create a better bitcoin? Is this machine that you're talking about is bitcoin?
Seeing that there is a rapid development in our technology everyday, it is not too far from reality that we may live to see a . Maybe we won't see it in a long time, but we can still see the concepts of it before saying goodbye to this world.
If you mean by a true AI a self-aware machine, this may never happen at all. Not that I'm implicitly referring to an existence of soul and such, but even if we are, nevertheless, able to recreate a self-aware mind in a machine somehow (as we basically do in our children), we may still not be able to understand what self-awareness conceptually is from a scientific point of view.