Seriously, after the latest round with the California CARB restrictions, the 2 cycle engines we are now using will be radically changed by 2010.
All kidding about laser's aside, the plain fact is that small engines are blamed for 5% of the air pollution problem in California. The environmentalists display posters showing 1 chainsaw equals the air pollutants of 10 cars.
Since, in California, they aren't going to give up their freeways or cars, guess where the crackdown will be focused!
One of the options is the catalytic converter technology, but imagine the heat from having a 300F deg converter 4" from your left hand on your chainsaw!
My best guess is that chainsaws will be very quiet 4 strokes, 30% heavier, with the rpm limited to 8000.