And WHERE will the other 97% go ?
I think it's useful to remember that on any modern engine, actual servicing in the sense of regular jobs that are needed to keep the engine running properly is becoming simpler and simpler. Change the oil once a year, air filter and brake fluid every 2 years, spark plugs and coolant every 3 years, plug in a computer to reset the service intervals and check for faults, all these are jobs that any competent DIY mechanic could do at home or decent local BMW specialist could do for you with no great problems.
The challenges come when things break or go wrong, and it's at this point where factory/custom built parts and their potential lack of availability come in. But as we've seen with previous generations of Morgan, if there's something problematic that the factory is unable to help with or only offers a massively expensive solution, there will be enthusiast owners who happily get to grips with the technology to sort out. Ultimately if something breaks and there's no replacement available, there will always be a local machine shop or electronics specialist who can make a replacement, and it could be a mistake to think this would be a more expensive solution.
This is true of all makes, and especially true of the more exotic or expensive stuff. A couple of years ago the ABS solenoid on my Td5 failed. The official Land Rover solution was a whole new ABS unit at £1800 + VAT, my local garage's solution was to send it off to a specialist for a rebuild which cost me around £400. Or look at how the owners of Bentley Continentals are replacing the high-level brake LED strips. Official Bentley method: remove rear window, long and complex job, costs an arm and a leg. Enthusiast's approach: break out the old one from above, insert new one, re-seal. Costs a couple of hundred.
My brief ride in a Plus Four was quite enough to light the fire of desire in me. They are flippin' fantastic cars and it's only the purchase cost that's preventing me from making the move. I would have no worry about getting the thing serviced or repaired even if I couldn't do it myself, but I almost certainly wouldn't bother a Morgan dealer once the car was out of warranty.