Well the PSLF program started in 2007, and 2017 is really right around the corner.
The odds of it existing are interesting, especially since lawyers are getting most of the press on the topic. The public is miffed that a lawyer can work for the government for 10 years collecting contacts and networking, get student loans paid off, and then go into private practice. However, the PSLF program is a law passed by lawyers themselves. I think the program has more staying power than we give it credit. I certainly think any proposed changes would grandfather in anybody who has already made IBR / PAYE payments before the change, because the lawyers will always protect their own.
What might really cause revolt and the termination of PSLF is more publicity about the current Georgetown Law deal, where the school itself pays your IBR/PAYE payments for the first 10 years (because the cost of ten years of IBR/PAYE payments has already been folded in to Georgetown Law tuition). Thus the student goes to law school for free, Georgetown collects in net its normal tuition, and the taxpayer is held liable for both 100% of the arbitrary Georgetown Law tuition and 100% of the 10 years of income-based loan payments. Georgetown could charge whatever tuition is wanted (even hypothetically a billion dollars a year) and neither the student lawyer nor Georgetown would suffer in the slightest. It's a genius loophole, really, one that you'd only expect from a coven of lawyers.
I'm surprised no medical school has followed suit.
Most medical students will make less than $2,000,000 in the first ten years beyond school itself. PAYE payments would be less than $200,000 total. Just jack up tuition by another $50,000 a year, and promise all applicants a free medical school education (if they can stay in public service for the first ten years). Would be quite interesting indeed.