I get what you're saying and the reasoning behind it, but older hardware has never been useful where power consumption is part of determining usefulness.
This is the biggest threat to the GPU economy – software breakthroughs that enable inference on commodity CPU hardware or specialized ASIC boards that hyperscalers can fabricate themselves. Google has a stockpile of TPUs that seem fairly effective, although it’s hard to tell for certain because they don’t make it easy to rent them.
I don't think we will need to wait for anything as unpredictable as a breakthrough. Optimizing inference for the most clearly defined tasks, which are also the tasks where value is most readily quantified, like coding, is underway now.