I know there's no way for you to verify this, but I'm actually an expert on this.
First, the chance of ANY changes in the next couple of years are tiny.
Second, if there are changes, they will almost certainly apply to people who are younger, like 50 or 60, if not younger, to give people an opportunity to adjust.
Third, in the highly, highly unlikely case that he is affected, any changes will be based on birth year, not filing year, so you won't be able to "beat the change" by filing early.
Fourth, if they do raise the FRA, I don't know if they will change the age at which delayed retirement credits end, which is currently age 70.
Note that you can apply for benefits up to 4 months before they start (
https://www.ssa.gov/help/iClaim_startBenefits.html) so you may want to file a few months early. On the other hand, you can file to start benefits for up to 6 months BEFORE you file (
https://www.ssa.gov/benefits/retirement/planner/delayret.html), so if you are a few months late, it doesn't matter: you'll just get retroactive payments for the previous few months.