Sony doesn't have
a) battery life
b) lens selection
c) battery life
d) ovf
You might read up on people who dump all their Canon/Nikon/Whatever gear and go full Sony ( or other ) and see how they fair.
The grass isn't always greener on the other side - sometimes, watering your own lawn is the way to go.
Battery life is so poor compared to the Nikon I replaced with the a7, and lens selection (for AF lenses) does disappoint at present, but I love being able to use my dad's Leica m-mount lenses on this and I don't miss the OVF of my Nikon at all.
I shoot mainly landscapes, so the one native lens I bought was the 16-35 f4, but have shot an anniversary party and the Seattle Pride Parade with the a7 and have not been disappointed (rented the 24-70 and 70-200 to shoot them).
Rest assured, the Sony is not perfect (what camera is, really?) and there are small things I miss from my d600 (mainly the ability to set copyright info in the menu system for EXIF, and the built in flash to control slave speedlights), but there are features the Sony has that Nikon doesn't and I wouldn't want to give them up. All I really want is vastly better battery life, but that isn't likely given the physical size limitations of the battery packs.