@kopite7kimi recently talked about what we might expect from the gaming GPUs in the Blackwell series. It looks like they might keep the same memory setup as the Ada Lovelace GPUs. This has been a bit disappointing for those who were hoping for a bigger change to a 512-bit interface.
One exciting possibility is that the GeForce RTX 50xx series could use a newer type of memory called GDDR7, following a recent announcement of this new memory standard by JEDEC. Even with this new memory, it's expected that the design will still use 16 Gbit memory chips, which means each chip would hold 2 GB of data.
The lineup could look like the following:
Sources: kopite7kimi Tweet, Tom's Hardware, Wccftech