[hedgehog]

There are several open BSDs.

[umanwizard]

AFAIK there's no evidence to suggest that permissive vs. copyleft license is the reason for the relative lack of success of the BSDs vs. Linux.

[pjmlp]

PlayStation and macOS kind of show what happens with upstream.

As did all the UNIXes that used to rule before companies started sponsoring Linux kernel development, and were quite happily taking BSD code into them, alongside UNIX System V original code.