For years I have used this mouse, 3,000 hours of Arma 3, 700 of DayZ and many many more from other games. When the cable eventually breaks, I will fit a new USB, when the switches turn to mush I will solder in new switches.
I'm far from a fan boy, especially when it comes to Corsair but the Scimitar, best mouse I have had.
In addition to that, for popular, "name brand" mice, there are often also tons of replacement parts available from China. You can basically re-build the complete mouse from parts.
Otherwise, as you've said, switches, wheel, the battery and maybe the cable, should always be replaceable (as long as you can solder).