There is nothing to trust, it is literally occurring on a daily basis as we speak. The PSLF option is part of the loan being taken out so the likelihood any changes do not grandfather current people with loans is very low. You could make some argument about the efficacy of republicans at stacking the courts that somehow could seek to completely undo this, but the likelihood there is the political will to do something like this is very low. PSLF is a lot different than wiping out 10-20k from everyone and I have heard of zero political will to remove it.
I personally paid back every cent and then 2k extra on my loans (grumble grumble), approx 1/4 million and did not do PSLF, I am not some evangel for this way, but it clearly is the right financial move for most people that went to med school without family/scholarship help. Being the right financial move does not mean it's the best life move but it is very often the best financial move and it's important for people to know that.