I've torn my labrum before. Twice. Not the end of the world, the surgery/recovery/therapy honestly isn't that bad.
First time was sophomore year of high school, when I dislocated my shoulder during swim practice. Didn't want to do the surgery but the tear was very severe. The surgery was in late December, came back and, after a few weeks of summer practice (nothing compared to what I had been doing the previous winter), I ended up making nationals for the first time. And I didn't do the rehab exercises nearly as much as I should have.
Keep in mind that I suffered a violent dislocation, which tore the labrum. If Pineda had suffered his injury in the same way, things would be much worse. Also, I was just a high school kid, lazy as hell, went to therapy a few times per week and hardly, if ever, did the in-home exercises. He's a professional athlete with a full-time training staff, etc., and he'll have his surgery done by the best of the best. The surgery is VERY simple, as far as surgeries go.
Just going off of personal experience here, I think he could end up coming back just as good as before. That said, I've never been relied upon to throw 98 mph fastballs. And I'm not sure how many pitchers have had this before. But as far as swimming is concerned, I got much better after the surgery. So take that FWIW.