We don't know for example what a larger model can do with the new techniques DeepSeek is using for improving/refining it. It's possible the new models on their [own] failed to show progress but a combination of techniques will enable that barrier to be crossed.

We also don't know what the next discovery/breakthrough will be like. The reward for getting smarter AI is still huge and so the investment will likely remain huge for some time. If anything DeepSeek is showing us that there is still progress to be made.