I’ve never heard of uncut wavers hitting storage or the market. These things are made to be used for whatever is needed at the moment. If you hear this news regarding “Ram cap sold out”, it means all available wavers they expect to be produced for that year have been allocated to whoever paid for them. If 50% of the wavers go into HBM, 30% into DDR including LPDDR and 20% go into NAND storage (i do not have the exact numbers, but i know that HBM needs around 3x the amount of silicon compared to DDR), then you are done selling your capacity - whatever happens afterwards does not make DDR5 appear magically on the market.
Only thing that could change that would be that the AI bubble crashes before 2027, then the allocation numbers will be changed.