It’s an interesting topic, and a few things have been said about it already relating to MusicBrainz, including by @rob here.
I don’t think it will have a large effect on the data in MusicBrainz, because the GDPR makes a specific exception for “archiving purposes in the public interest”, which MusicBrainz, Wikipedia et. al clearly are (not sure about Google though).
By the way, you may want to add “gdpr” as a tag to your topic for future reference. 