Personally I'd like to see them drop Tech Drive and revert back to a modern take on the 500 series/Dual Sanitronic. Squeeze the current G3-Avalir II motor into a replica of the classic 500 series shell, transfer over the fancase and emptor from the Sentria/Avalir (since that configuration affords the best airflow out of all the Kirby machines), perhaps optimize the old-style floor nozzle to maintain or beat the current standing of 150 CFM, and they would have a winner. While the G series machines are great (I have an Avalir and used to have a Sentria I) I think that it's time to bid adieu to the design and revert back to their roots. I have a Legend and a DS50 and neither of them have Tech Drive yet are still easy to maneuver, plus there isn't a parasitic loss in the form of the motor having to send power to the wheels via a transmission in addition to the fan and brushroll.
Of course I don't think that the above will happen as people are fickle and would turn down a perfectly good vacuum because it looks like it's from the 60s. They already have one strike against them for having an outer cloth bag -- for too many people these days, a cloth bag equals old tech even though a machine equipped with one typically outperforms basically everything sold at Target, Walmart, Sears, Best Buy, and so on. People in general do not care to educate themselves on the technology behind their appliances, cars, and so on. They just buy what looks cool. Having them bring back something like a modernized Dual Sanitronic 50 may turn off a lot of would be buyers, so the rational side of me says maybe it would be cool for enthusiasts and open minded people but not the general public.
At the same time, I feel that maybe Kirby should keep on going with the G series design -- there's nothing bad about the G series, it's just that Tech Drive isn't all that necessary. The advantages are that it does work well, it is time tested and parts are more or less interchangeable from model to model. One more iteration of the Gxx/Sentria/Avalir only means more parts for the forseeable future.