Really happy with my D500! Until a mirrorless version comes out that can provide the same or better level of performance at a lower than full frame price.....perhaps staying with the D500 is the way to go. For most other cameras, I think there are pretty good mirrorless options already.
I was using DSLR until I found out mirrorless has been more accurate, faster, no mirror shake and rarely blurry photo also so much smaller. Many noticed mirrorless rarely have misaligned lenses too. I really hate mirror vibrations, destroy photos.
Recently grabbed my sis RP, was surprised at the colors and focus speed. far cry from Canon 5d4 5DSR which I used previously.
Been using A7R mk1 since launch, got a 2nd body for NZ trip. Using adapter for A-mount lens, A850 been sleeping since then.
Weight is an issue for non mirrorless, as some time lapse devices cannot handle heavy load. We also getting old by the days, even with wheels bag, also need to carry when upslope etc.
Mirrorless are catching up, as long not much different, I consider into mirrorless long way back