It all depends what you mean by "old tickets." The tickets changed on January 2, 2005. I went to WDW in May 2005, but I bought the package in October 2004, so even when I arrived in May 2005 I was given the "old tickets" upon check-in.
The tickets I had were length-of-stay tickets -- we were there for 7 days, we had 7 days hoppers-plus, but the tickets expired after our last day as resort guests. Say I didn't go to parks for 2 days of my 7-day stay. In my case, I would NOT have had 2 days left on my passes, since, as I said, the package I bought included length-of-stay tickets.