Looking at BMO's 2015 Annual Report I find only two mentions of the word Diners, both in footnotes. I suppose it is possible that they are simply going to let their franchise agreements for Canada and the USA run to expiration and walk away, leaving Discover to operate it directly or award it to another issuer.

It was clear at the outset that they were primarily interested in the Corporate accounts. If that has not worked well it probably would not pay to sink any money into the moribund consumer side.