Open source doesn't reduce the issues with people writing to the implementation, not the spec - leading to unintentional interactions and trivia suddenly becoming impossible to change.
If edge dies, and FF shrinks further (both of which seem likely), FF will in effect be reduced to an alternative implementation of chrome; not a implementation of a web browser. Both Edge and FF already include chrome-quirk emulating features; you can expect those exceptions to become the norm.
Apple - for all it's wealth - isn't likely to bother bucking the trend here. The same forces pushing MS affect Apple too; and given their high-end only marketing and various political factors, they will be completely ignored in much of asia - and that's a lot of devs creating a lot of stuff that is likely to depend on chrome-only features eventually.
If edge dies, and FF shrinks further (both of which seem likely), FF will in effect be reduced to an alternative implementation of chrome; not a implementation of a web browser. Both Edge and FF already include chrome-quirk emulating features; you can expect those exceptions to become the norm.
Apple - for all it's wealth - isn't likely to bother bucking the trend here. The same forces pushing MS affect Apple too; and given their high-end only marketing and various political factors, they will be completely ignored in much of asia - and that's a lot of devs creating a lot of stuff that is likely to depend on chrome-only features eventually.