"The invalidation of Yard-Man will help employers, but the CBA's language as a whole and -- if the agreement is ambiguous -- appropriate evidence of the parties' intent remain key to resolving whether the employer has retained the right to amend, modify or terminate retiree medical benefits.... Durational language limiting retiree medical coverage to the term of the CBA can limit the employer's obligation to continue providing retiree medical benefits, unless the durational language is diluted by other language in the CBA that indicates retiree medical coverage continues beyond the contract term." [M&G Polymers v. Tackett, No. 13-1010 (U.S. Jan. 26, 2015)]