If you want to know the RPi's strategy about the RP2040, I guess you should ask instead of guessing. Who knows if they're gonna release RP2040 variants with a stacked Flash die. Maybe. Maybe not. I guess it will all depend on demand and their strategy. I'm personally not convinced of the point, as the prices of the RP2040 and RP2350 are very close (except at some distributors currently, but that's probably a matter of stock management) and I guess those more likely to stick to the RP2040 are those who already have a design around it. But who knows, market will tell.
What's interesting behind this question though is that apparently, many people who were kind of sold on the RP2040 seem definitely not on the RP2350, possibly due to its errata, or the currently (relatively) "inflated" price on LCSC/JLCPCB, or a combination of both. Possibly also, as always, the perspective to have to update their knowledge and developments (if any existing) to the RP2350 which brings a number of changes for sure (but via their SDK, there's not a lot of work to port an existing firmware to the RP2350.)