Definitely no free lunch, but if you're going into a field where you have a long residency and pursue fellowships after it's still a good option. Heck, it's even a good option for neurosurgeons and ortho people if they do fellowships as they may only need to work for a qualifying program for 2-3 years to get that loan forgiveness. If you're sitting on 350k+ in loans then it could very well be worth it.
As for 2019 being "the year to watch", here was the logic the speaker, a "medical finance expert" (Paul Garrard, ex-VP of AAMC student financial services), gave when he spoke to our class during graduation week about medical debt. Yes, a very small number of people have had forgiveness, but that's assuming they made their payments on time every single month for 10 years, which accounts for only a small number of people. The first significant cohort receiving forgiveness will be this year (2018), and the reports on this group likely won't hit the desks of congress until 2019. So according to him that's the year we're likely to see legislation proposals to either significantly change or eliminate PSLF, as that's when legislators will see how much this plan is actually costing the gov. Idk if that's how it will pan out, but that was his reasoning, which seems pretty accurate and likely imo.