Hi Cayenne!
I wouldn't worry too much, since, thanks to companies like Novoflex, EF lenses can be adapted to other non-Canon cameras, Sony, Leica SL, Panasonic etc...
True....BUT, for how long will that work out?
Per my earlier post...it depends on how long Canon and other mirrorless camera bodies will incorporate electronics/software/signals that will through an adaptor work the aperture on the EF lenses.
My theory was that since the EF lenses don't have any way to manually set the aperture, at some point, newer camera bodies may stop bothering to control EF lenses as they become older and older.
It seems the lenses that are getting new leases on life via adaptors on mirrorless bodies, are the fully manual ones, or at least the ones that can be set manually.
It would be nice if modern lenses could be set to allow manual aperture mechanically, and then switch over for auto control by the body. That would ensure greater longevity on lenses....otherwise, these great lenses of the past will be rendered unusable.
EF lenses will be in the category some day potentially.
Then again, I guess if the future adapters are "smart", then they might be able to translate whatever protocol is in that body of the day into the old signals of the older lens.
But, that's gonna start driving adapters to be a bit more $$$ and specialized over time.
OH well...always fun to see what happens in the future.