It took how long for Apple to update the mini 4 to the mini 5? Maybe just be happy that Apple actually did refresh the mini.
Imo the mini is paired with the iPad Air. So they will go with the same cadence in terms of hardware refreshes. I have a feeling we won't see newer iPad minis/Airs until next year, using the same A14 as the iPhone 12. Now if the A14 is shown to be more efficient (Apple putting smaller batteries on the 12 vs the 11 series), then maybe we will see a redesign. OTOH, personally I don't see anything wrong with the current design. Bezels on tablets are still useful in terms of usability. Sure, it might look dated, but realistically, Apple has almost no competition in this space.