I agree that it is unknown when such an AI will come around. But hardware limitation problem is more nuance than just GPU power. The brain is analog and in a way, the current LLMs and neural networks are an approximation of an analog computer. There are current research into making an AI dedicated chip or even an analog computer specifically for neural networks. Digital was easy to work with but when it comes to fuzzy stuff like AI, there are better ways.

We used to think 100mph was the fastest speed we could achieve even with machine (back when trains were the cutting edge). New tech will change things quickly, all we need is one breakthrough and things will fall into place.