Taking up on the topic of chain saws of the future I would like to deal with three categories and what has been done by manufacturers in the past.
Diesel powered chain saws.
These were introduced by manufacturers in Sweden in the early 1950's. I have in my collection a Comet chain saw that is diesel powered, weighs only 14 lbs. complete with bar and chain. Jonsered bought the company and produced the saw as their RAKET. No torque, runs extremely hot, (to the point of being dangerous in the woods in summer) starting problems particularly in cold weather.
Turbo Charged. in 1963 Remington experimented with a saw series 880 direct drive and gear drive.
They took the air into the carburetor/air filter chamber right off the flywheel which produced a turbo effect. Jonsereds, Husky and Poulan has it in a somewhat similar version now. The 880 was a real performing saw with a 5.8 cu. in. engine. The turbo was definitely effective. Work for 3 days without cleaning the air filter too.
Turbine powered.
Dolmar built a saw in the 1960's with a Wankel type rotary engine and it would really go, only problem was no torque and heavy. How do you get gut wrenching torque from a 2-cycle motor?? Stroke and displacement thats how. Several manufacturers have produced twin cylinder chain saw units that would really scream but if you put anything more than a 15" bar on them they would not perform. Where I live the biggest selling bar size is 33". You have to have torque to get performance. Certainly in other parts of the world where a 15" bar is standard more RPM is desireable and small displacement engines will work. In 1963 McCulloch built a saw model BP-1 that was years ahead of it's time. It had two pistons, one doing the work and one that was a perfect balance of the other, absolutely no vibration, 14,000 RPM no problem, a gear box provided a workable chain speed. The chain was automatically sharpened and cut extremely well. It had fuel injection. It was light and well balanced.
My point is.... most things that are brought out as new have been tried at least once before. The idea might not have worked that well the first time around because of the state of technology at that time. Today with the cost of developing a new model of chain saw any manufacturer is going to have to go with proven technology and design features. The boldest venture around is Dolmar with their 50cc 4-cycle chain saw. Check their web site for details. The last time a chain saw was built with a 4-cycle engine was 1934 or so.........
Chain Saw Museum