Maybe GDP will suffer but we've always known that was a mediocre metric at best. We already have doubts about the real value of intellectual property outside of artificial scarcity, which we maintain only because we still trade intellectual work for material goods which used to be scarce. That's only a fraction of the world economy already and it can very different in the future.
I have no idea what it'll be like when most people are free to do creative work when the average person doesn't produce anything anybody might want. But if they're happy I'm happy.