I won’t attempt to describe the implications. For that, your best bet is to read it from one of the experts, Ethan Siegel: The First Detection Of Gravitational Waves Validates Einstein In A Whole New Way!
Let’s hope those implications aren’t this.
Both General Relativity and the Standard Model or particle physics keep getting validated. Neither is blinking, but we know they’re ultimately incompatible with each other. Today, I think that tension ratcheted up a little more.
On the plus side, we’ll probably be able to learn all kinds of interesting things about black holes in the years to come by studying their gravitational radiation. And if we ever are able to study primordial gravitational waves from the early stages of cosmic inflation, it may give us insights into regions of the remote universe orders of magnitude beyond what can currently be observed.