I believe the first year they offered it was the year they put expiry dates on all the tickets in the middle of the Canadian offer. I might be wrong, but I think the expiry date was then added to the Canadian tickets, as well.
No one knows what Disney is going to do. I know the UK folks don't seem worried that their special tickets will change. This ticketing change wasn't even big news in the UK (from what I understand). That said, the offer says "for as low as" and doesn't specify how long they are valid after first use. It could be that as of the 16th, the offer will still stand, but will be a discount to the new tickets rather than a flat fee.
My advice... if you know when you're going and for how long, buy now.