Bret,
In '96, my wife took an early (25-years time in service) cash buy-out, when Ma Bell was downsizing and the Baby Bells were born. A stipulation of her separation contract was lifetime no-premium medical coverage for her and me. There were, however, small co-pays for things like office visits and medications. Her becoming Medicare qualified did not change the company's obligation, because it covered what Medicare Part A, B, and D didn't. The company's cost was likely lower, but that was all.
Then, ol' Barry's anointment screwed it all up. On 1-1-15, a part of Obamacare went into effect, dictating companies that had been providing premium-free health insurance to their retirees could no longer do so. (Where were the rich and powerful union bosses, then? Vacationing in the Bahamas? Hmmm . . .) In my wife's case, the company contracted with a third-party health insurance exchange (AON), and we had to select our coverage from a list of insurance companies and their plans.
The company created a "medical insurance account" for my wife. Each year the company approves a certain dollar amount for her and a smaller amount for me. We pay monthly premiums to our insurance company (Blue Shield of California) and the company makes monthly reimbursements till the dollars are depleted. The plan we selected (Medicare Plan F) has the most coverage and the highest premium. The company reimbursements usually run out in September.
The part of the contract -- premium-free health insurance coverage -- the company and my wife agreed to was made null and void by ol' Barry. Now, we have to pay one-fourth of our annual premiums.
Any legal and binding contract is only legal and binding till a non-elected think tank policy writer convinces the Capitol and the White House it's in their best interest to decide otherwise.
Hope this helps answer your question.