We do not have a date from Raspberry Pi yet for an updated version of the Raspberry Pi Pico 2 with the updated A3/A4 stepping RP2350.
It is our understanding that these will be introduced by Raspberry Pi once the current stock of Pico 2 boards has been depleted.
Once we have the updated version, our product pages will be updated to show that the new version is stocked.
For more information on the RP2350 stepping change, see the following Raspberry Pi news article: https://www.raspberrypi.com/news/rp2350-a4-rp2354-and-a-new-hacking-challenge/ - where the FAQ states:
Will Pico 2 products switch to A4?
Eventually, all Pico 2 products will use the A4 stepping. While the A3 stepping will not be made available to silicon customers, approximately 30,000 units of A3 inventory will be used to build Pico 2 and Pico 2 W products.