I think the next trailie will be a DRZ400 or perhaps a Kato 300 electric start two stroke unless something more suitable comes along. I love the little TTR250 but I'm a big lump and need a tad more power. A friend had one with a 305 kit in it which sparked it up a but but it was still not quite enough for moi! I love the technology of the new generation bikes but think that the big factories not offering a low tech alternative for the average weekend punter may eventually come back to haunt them. Not everyone rides Supercross or rides open enduros.
Look at history...The Yamaha DT1, Honda XL250 Motorsport, PE Suzuki, IT Yamaha, Yamaha XT500, and XR400/600 were basic, simple, easy to live with bikes that were virtually bulletproof if treated properly. They all sold in their millions. I had a Yamaha TT600 on which I raced dirt track, rode it on the street, trail rode many weekends and even rode an early Thumpernats meet. It was also the best wheelie bike ever made. In over 8 years of ownership it had only one top end overhaul, a cam chain and a couple of sets of rings. It still had the original piston, valve springs and valves in it when I sold it and it was still running fine.
Try that on your new generation 4 stroke.