This is a relatively minor event. For most any actual Wikipedia author, nothing will change. That's because these global rules merely codify a minimum standard that any of the top-50 or more wikimedia sites have long had on the books.

The purpose is to expand these rules to some of the small properties (Gaelic Wikinews or whatever) where they lack due to omission: admin teams are small, resources scarce, etc. No community has ever decided "no, we believe harassing women is great" (is there a gop.wikisomething.org?). The just haven't gotten around to putting it in writing.

It'll also make it easier to work across projects, because you won't have to familiarise yourself with the nuances of local rules in easy cases. Sort-of like the EU's harmonisation of customer rights across jurisdictions makes it easier to order from France or Italy.

But, mostly, a non-event. I'm sure there'll be hot debates and open letters and then everyone will forget about it.