M$ adopting Linux will be similar to the RHEL/Fedora/CentOS model = Winsux 10 Ent/Winsux 10 Home & Pro. The difference is that the trade-marked Winsux 10 Home & Pro will not be free software(= subscription-based.?), unlike free Fedora/CentOS.
....... If so, very few 3rd-party Linux developers will contribute to the non-free Winsux "open-source" project owned by M$, unlike the present free Fedora/CentOS open-source project owned by Red Hat Inc/IBM.
Another comparison is the free Chromium browser, Chromium OS and Android open-source projects owned by Google/Alphabet Inc.