I think it is clear that mirrorless is evolving from small and light in weight to larger and heavier to serve the needs of the professional market.
If Leica, Panasonic, Sigma and others want to compete for serious amateurs and professionals, they have to make cameras with pro features…. fast glass for photojournalists, big buffers and adequate size to handle comfortably with large lenses for sports shooters, fast tethering ports for studio shooters, and serious image stabilization and heat-sinking abilities for videographers. We’ll probably see 6K or 8K video in a year or two.
These cameras are not meant to replace small M-style rangefinder cameras, they will serve different markets.
Compare the size of the new S1R to a Nikon D850, I’ll guess that the Lumix is slightly smaller and it is lighter as the Nikon tops 1000 grams.
The casual amateur market is drying up because phones have replaced small cameras, so we’ll see more companies competing for the higher-end market.
I do feel that the camera companies will also continue to produce high-quality small cameras for the foreseeable future. Hopefully, some of the new features will start showing up later in the smaller camera bodies.