I find it curious that everyone else is recommanding the multi lenses systems. Am I the only weirdo who's ok with his second system havin 1 focal?
My idea of a mirrorless camera is primarily a weight and smaller form factor advantage. This will be perfect for family outings and/or where carrying a huge backpack isn't such a good idea. So, as a personal preference a second system with a single 50mm lens is fine by me.
For interchangeable lenses, I already have a fully stocked kit. To me, it makes no sense in trying to save a few grams while carrying 4-5 lenses. I might as well buy a much lighter tripod
1DX, 5D3, 600D, RX100
16-35L, 24-70L II, 70-200L II, 100-400L II, 50L, 85L II, 135L, 17TSE, 24TSE, 40, 100 macro, 18-55 II, 55-250 II, 1.4x III, 2x III, 600RT x 4
When it comes to gear, it is better to vote with your wallet. Bitching on online forums like a lunatic doesn't get you anywhere!