If all goes "well", starting work on a new DDR5 fab now would result in having it ready to go when DDR6 hits the market:

https://www.techpowerup.com/339178/ddr6-memory-arrives-in-20...

So the supply side won't get better until about 2028.

I suppose you could hope for an AI crash bad enough to wipe out OpenAI, but unless it happens within the next few months, it may still be too late to profitably restore the DDR5 production lines now being converted to HBM, even if the broader economy doesn't tank:

https://www.reuters.com/markets/europe/if-ai-is-bubble-econo...

Perhaps not coincidentally, that Reuters article was published the same day OpenAI announced that it had cornered an estimated 40% of the world's DRAM production:

https://openai.com/index/samsung-and-sk-join-stargate/

https://www.tomshardware.com/pc-components/dram/openais-star...