I'll just make a few points...
1. It is almost certainly technologically feasible to develop a replaceable digital module for the M system. The GXR is basically an M camera minus the RF mechanism, and it is both smaller than the typical finder-less film body (Ikon SW) and produces perfectly fine pictures. Leica may not be able to do it, but Leica as an electronics company has always lagged behind the Japanese firms...I don't have a single doubt that if Nikon or Sony really wanted to make a module RF happen, they can build one.
2. Leica makes more money by offering cameras as-is, and forcing users to upgrade with their cycles. You are not a good Leica user (in Leica's view) if you didn't ditch your M8 for an M9 and then ditch it for an M240 when it came out in 2012. Obviously there are plenty of people that can both afford and want to do this, so Leica, sad as I am to say it, can choose to not care about the rest.
3. Just getting this out of the system, but Leica service is mediocre at best. Turnarounds are usually much longer than regular Canon or Nikon services if you live in the US, and service is downright lousy in most parts of Asia. The Leica official retailer in Beijing wouldn't even send a lens to Solmes on my behalf, and insisted that I mail it myself to Germany. Yes they support lenses long after ceasing production, but I really, really, really wish Leica could provide speedy repairs for its current products.
So yes, Leica and Digital RFs are an expensive and occasionally frustrating hobby. I would try to complain very loudly and see if Leica will provide a discount or fix it for free. In the long run it's probably best to stick with third-party serviceable lenses and cheap Japanese prosumer bodies...for the price of upgrading Leica digitals you can literally throw a used A7 into the trash can every year 😀