Any drug submission that supports shelf life via ALT data will be expected to also say "and we're doing real time testing to support this", and FDA will expect the follow up real-time data.
But if, in reality, that drug only lasts for a strong 5 years, after which time it loses effectiveness, especially in high humidity or with high UV exposure. We could catch this with real-time tests and adjust accordingly - before it actually affects the general public's health.
For the vast majority of manufactured products, HALT makes sense because any uncertainty that remains after testing is not likely to harm users. But with some of these drugs, any uncertainty, even after HALT, could cause major problems for users. And it seems that the FDA is unwilling to accept that risk. But as far as I know, the FDA is actively seeking methods for performing HALT that produce accurate and repeatable results.
Given the amount of money spent on medicines, I really think there is a good moral business case to identify the correct expiration dates and save money for people.
We just went through the Health care ordeal. Money saved anywhere is money saved for people who desperately need healthcare to work for them.
Given that it's the very same party that would be doing the testing for expiration dates, I kind of doubt they would research this out of the goodness of their corporate hearts. Effectively the same outcome could be realised without the effort of extra testing anything: by just lowering the price of medicine a bit; big pharma would make less money, the public would have more medicine for cheaper.
A case could be made for legislation that obliges free replacement of out of date medication for the original purchaser, perhaps with a small surcharge.