I can envision a machine that could eliminate almost all the lifting and turning and would be very high production, but it would be expensive and require support equipment. All it takes is a lot of money. My ideal is to take a sectional conveyor. Each section being just short enough for the minimum lenght wood you want to produce. Make it where the sections can be adjustabe to handle the longest pieces of firewood you want to produce. Between each section mount a vertical saw, similar to a gang saw. I would probably choose a chain and bar instead of a circular saw simply because of cost and limited cutting dia. The saw would be mounted on each conveyor section so that it would move as the sections are extended or retracted. Throw a 10-12-14 ft etc. lenght log on the conveyor. Saw the entire log into rounds at the same time with the saws then advance the rounds into a automatic splitter similar to the Splitta 400, except make the splitter big enough to handle the largest rounds your saws would cut. You could also make it where you only cut 3 or 4 rounds off a log at a time. Add a long conveyor to remove the split rounds away from the spitter. While the splitter is processing the firewood, the operator can use a loader to get another log ready for the conveyor. The operator could use a remote control to start/stop the machine.. I have no ideal what it would take to power such a rig, expensive I am sure, but one man could produce a of wood in a day and never break a sweat.
In such a high production capable splitter, and the lack of manpower needed to produce the wood, one would think they have elminated a lot of labor cost. Maybe, until you start thinking of bagging, or stacking,and delivering. If your going to produce that much firewood, you are going to need to move it, preferrably to the end user, not just piled on your lot. This is going to take manpower, altho the operator could just process wood for a few hours a day and make deliveries the rest of the day.
For support equipment, besides the loader, I would want a debarker to remove the bark and cut down on the mess, as well as the dirt that would come with skidded timber. bark is another high value product to be sold in landscaping. You would also need some method of getting rid of the sawdust. Then you would need some sort of bagging system to catch the splits as they come off the processor and a shed to store the bags under. I would probably want to set all this up on a concrete slab. I would also think about installing a set of truck scales and sell the wood by weight instead of cords. With the scales, you can tell just how much the suppler is hauling to you and how much you are delivering to each customer. Also makes it easy for someone to come to you to buy wood so you dont have to deliver. Any time you can save by not being on the road is more money in your pocket.
Sadly, most of us on here dont have the market, money, or time to justify such a operation, but that doesnt stop us from wanting the biggest, baddest splitter money can buy.