Hi Tyler,
There is no incentive whatever so it will never happen, sure a prototype could be built but no manufacturer would think twice about it unless there was some financial benefit for them. Millions of engine designs have been tried over the years and eventually it all ends up back at the cheapest current design which is the 4 stroke OHC motors. The reality of it is if you consider the cost of any mowers back in the 50s/60/s at several months wages just to pay for it compared to the hours, not months needed to buy one today, the consumer is way better off buying a cheapie from wherever and just buying a new one each year
