I think there are two separate questions here - is it likely to be upgraded, and is it likely to go out of production ?
IMHO, it is unlikely to be upgraded. AFAIK, no other competitor has a 5x macro lens, and it's performance is good compared to other macro lenses. In this situation I don't see any reason for Canon to upgrade it, though possibly newer manufacturing processes making it profitable to redesign the lens, or Canon knows about a competitor going to announce a better lens.
Canon would produce the lens as long as it can sell it for profit. Considering the lens has no competition and is rather cheap (= Canon could raise it's price to keep it profitable), I'd guess it would only go out of production if sales dropped through the floor - which I think is unlikely.
My guess is the lens might go out of stock until a new batch is produced, but not out of production.