I agree, though I believe we are finally seeing change. The basic design of airplanes will always remain: wings, a fuseulage, some kind of propulsion and instrumentation, so your basic design will always remain (until possibly the very distant future). With new composite material construction we have better wing designs (complete without rivets), and are able to shape the bodies of aircraft to new and more aerodynamic specifications. New instrumentation (like glass cockpits) is finally starting to leak down into the mainstream of avionics. Newer and better engines are up and coming, with better fuel consumption and more power output due to more efficiency. Just look at Diamond's lineup: the DA-42 Twin Star, the composite twin that burns 9gal / hr TOTAL. It comes with options for anti icing and a glass cockpit for a reasonable price (this first hasn't yet been delivered, so we will ilkely see a few kinks to be worked out...). The Cirrus and Katana are also innovating designs, simple with their fixed gear, yet strong and fast with their composite construction. The DA-40, Diamond's four place single, will have also options for a glass cockpit soon. The way we use our avionics will change as well. Would you have recognized a GPS unit way back in 1960? How about a linked weather display, giving up to date weather conditions at all airports with a reporting station? The one area I believe still has a lot of room for growth is engine design. We need turbine reliability in piston engines which will require a revamp of engine design. We need lower fuel consumption and more power output at the same price. We will eventually need to switch fuel sources, as the price of 100LL is rising, and the supply is diminishing. Desil is an option, and so is Jet-A. Who knows, maybe some kind of fuel cells are in the crystal ball. These kinds of engine changes will only come with new materials and construction, but it is something we will see in the future. The problem is phasing all of this in. With such a strive for uniformity, it is difficult to even add handheld instrumentation under the FAA, much less change fuel sources. Necessity will instigate the change in time, but for now we can rejoice in new airplane designs, cockpit instrumentation, and slightly better engines.