Seriously, I think one of the Jap companies should build a 'low budget' & 'low maintenace' motocross & enduro bike. Two-stroke, air-cooling, twin rear shocks, something where kids of today can just go and ride and ride and ride and ride, like we use to. Who cares if it's down 5 hp, building the recreation market will boost all the genres of the sport.
Motocross & enduro versions being the same bike with lighting removed, offer wide-ratio gearbox and different suspension springs for those a little more serious but still a good basic bike for the budget rider.
If I could get some financial backers I'd start making them in Australia (sourcing selected components from China), the world market would snap them up.
Im not entirely convinced that the bikes we reckon would sell in the huge quantities that we would like to think
Until recently you could still buy an XR 200, DT 175 , ER 185, RT 100 , and other air cooled drum braked simple machines (i think some of these models are still available today in some markets ) but i dont recall the public buying them in large quanties and going trail riding
I think the world has moved on and to todays motorcycling public these models are seen as old fashioned and very uncool
I can only think of it as being when i started riding in the mid 70s somone suggested instead of a new RM 125 we should convince Francis Barnett and Dot to re tool and turn out some 1950s models as its what the public wants at grass roots level
Back to the original question , i would love to be able to buy a new Suzuki RM 370B and have a regular spares supply
However i would also want a race series where Modifications were limited to what was available in the day
ie no modern adjustable shocks or fancy fork valves etc