It is not an issue of processing power, it’s a problem with the basic operating principles of LLMs. They predict what they “think” is a valid bit of text to come after the last bit of text.
Sure it could be verified by some other machine learning tool, but we have no idea how that could work.
But I strongly doubt LLMs are a stepping stone on the way to true AIs. If you want to get to the moon you can’t just build higher and higher towers.
Also quantum computers aren’t really suited to run artificial neural networks as far as I know.