I don't see why there wouldn't be, it's cheaper to manufacture with seemingly no downsides. They probably won't revise the 4GB and 8GB versions until their stocks of the original stepping are used up though, and once they do introduce revised versions it may be a lottery which version you get for a while.
I'll bet they just slipstream them in. There was a huge backlog of the 8GB, that now looks pretty much cleared out. So it could be awhile before the D0 show up.
TSMC charged just a hair under $4000 per 16nm wafer in 2020.
Wafer calculators at 0.2 defect/cm2 on a 300mm wafer gives 950 fully-good dies out of 1061 for the old die (~89% good) and 1469 fully-good dies out of 1584 (~93%) for the new dies.
Dividing that out gives $4.21/chip for the old chip and $2.72/chip for the new chip. At $80 for an 8gb board, that represents a ~1.9% increase in profit per board. For the $60 4gb version, it's more like 2.5% increase in profit per board.
In real-world terms, if they sell 10M Pi5 units with the new chip, they'll have an extra $15M in the bank in saved production costs alone (minus whatever costs to strip everything out and tape out again). Furthermore, the new chip gets cheaper with every chip they make as the R&D costs get more and more diluted.
