mini form factor with single-lens, no MagSafe, sub-6GHz only 5G would be great. Not sure about the single-lens though as Apple will have to redesign the back, which neither SE1 nor SE2 received.
By 2023 non-SE iPhones might well have 3 or 4 cameras, so keeping the current mini’s camera setup could be considered very basic by then. They could definitely drop MagSafe out of it, which is a waste of phone space & energy, as it is now. The current mini’s screen is amazing, though, so I hope they do not cheap out on that.