Right, but besides 2015 being the year of the future from Part II it also marks as the 30 anniversary of the first film. So I can see why they would commemorate the event from that film instead.
Of course most of us are hoping to celebrate the Part II future in a bigger way. The problem is we can't expect the same level of detailing for the 2015 square as seen in the movie. That set was for the movie which the studio paid for as they expect bigger returns through the box office. But I don't see Universal spending that amount of money to rebuilt that set purely for fan celebration.
But if they do it, it's a great opportunity for Universal to bring in thousands of fans during that week. People pay to come and visit the square, get photos taken and participate in different activities.
I can't get into more details of the WGB 2015 event as we are still in planning stages, but we're striving towards making it the best and biggest BTTF event yet. The WGB 2010 event was for a week long, but this will be mostly focused on a single day. The total number of days celebrating the event might change, but it will be likely only on Oct 21, 2015.