My source of info is firsthand experience, and the person in charge of coordinating the rehab of the Contemporary resort with Buena Vista Construction Company. His job was officially eliminated in September (he moved to Guest Relations afterward).
The room numbers from the North Garden (all the 7000's and 8000's) have been COMPLETLEY removed from our and central reservation's systems (never happened during the rest of the rehab). If any rehab had begun on the North, there would've been rooms there coming back on to sell already. They have absolutely NO reason to close the entire building at once for the kind of rehab that was done to the rest of the resort. When they were refurbing the South, (and the Tower for that matter) there would be rooms in one section on the bottom floor that were finished being refurbed, second floor that were being worked on, and top floor that hadn't been touched. You don't fence off half of the parking lot for something like that. NGB has essentially been quarantined.
I also had to help remove all of Front Desk & Bell Service's items out of storage in the North and move them over to the South Garden, while South Garden was still under rehab. Now tell me, WHY would we move items from a storage room in a building that hasn't been touched, into a building that was then in the process of being refurbished?
Consider the extensive site prep work that will have to be done for any new building going into that site. Sight lines have to be observed. Local ecology has to be taken into mind. Ground prep has to be done. That takes a lot of time, putting it in line with the 2008-09 time line you're suggesting.
You know, I can argue this with people that are on the outside until I'm purple in the face as the jackets on the front desk. I could just let this go and see where all the wild speculation goes. I'm honestly just trying to be informative. I personally would've LOVED to have kept the resort buildings the same as they were when it was opened. I don't like the idea of DVC being there, or the idea of another 15 story building being built beside the existing Tower. Knowing what I know, I swear, if North Garden Building isn't rubble by at least February, I'll eat my nametag, and you can hold me to that.