I expect the next breakthroughs to be all about efficiency. Granted, that could be tomorrow, or in 5 years, and the AI companies have to stay all at in the meantime.
If there's a step-function breakthrough in efficiency, it's far more likely to be on the model side than on the semiconductor side. Even then, investing in the model companies only makes sense if you think one of them is going to be able to keep that innovation within their walls. Otherwise, you run into the same moat-draining problem.
That said innovation on the model side is more likely to come from a 10B-funded startup that still has some money to spare on the brightest researchers on top of giving them all the data and compute they want to play with.