WWDC 2023 is coming on June 5 - Here is everything you need to know about the event!
Considering that the iPad mini will be a cheaper price modell than the current iPad, I believe 8GB and maybe 16GB is going to be the max amount of storage that you're going to get with the iPad mini.
I'm thinking we'll see either one of these lineups:
16GB $299
32GB $399
or
8GB $249
16GB $349
32GB $449
and then whatever extra they charge for 3G/4G cellular