A Glock "Gen 6" that features grip angle changeable backstraps would be very welcome. It would solve one of the chief complaints some folks (myself included despite shooting glocks for 20 years) have with the design, while adding almost nothing to the production cost.
With swappable grip angle backstraps, you can go from ~1911, to CZ, to Glock grip angle, whichever points most naturally for the shooter. Lone Wolf has had this for like 10 years with their Timberwolf frame.