Professional photographers often have $10k+ invested in lenses so switching systems isn't something they'd be likely to do for an incremental upgrade. Some have switched to the Sony A9 though.
For me personally I had nowhere near that much money invested in Canon glass, so switching to Sony wasn't as painful (I pre-ordered the Sony A7iii but haven't received it yet).
Given that the $2000 Sony is out-reviewing the $3500 Canon 5D markIV, it's getting a lot of attention and I'm hardly the only one jumping ship. I think it's safe to assume that Canon/Nikon will respond with pro level mirrorless cameras as soon as they're able to.
For me personally I had nowhere near that much money invested in Canon glass, so switching to Sony wasn't as painful (I pre-ordered the Sony A7iii but haven't received it yet).
Given that the $2000 Sony is out-reviewing the $3500 Canon 5D markIV, it's getting a lot of attention and I'm hardly the only one jumping ship. I think it's safe to assume that Canon/Nikon will respond with pro level mirrorless cameras as soon as they're able to.