I think battery powered electric propulsion is the future for light aircraft. Most private flights are an hour bimble that is within reach of current battery technology. It is quieter which matters more than ever with the BANANA's trying to shut down so many GA airfields and it is the definition of green which gives us a way to push back at the GA haters, particularly with SEP's now mostly burning leaded fuel. The Billions being spent on car battery technology is rapidly driving battery prices down and battery energy density up.
I think over the next 10 years we will see electric light aircraft dominate flight training and new homebuilt aircraft which have much lower regulator barriers to entry. The current cost to overhaul a C 172 engine is approaching 40 K US including the re and re. The game changer will be affordable STC conversions to the current common GA types.