Also, there are lots of other unexpected things.
For example:
-we don't know how price drops will affect anything
-we don't know if MS will buy a big Japanese studio (like Koei) and start doing decently there
-we don't know when MS will have RROD fixed
-PS3 pricing will have a BIG effect on things
-we don't know the exact time that HD-DVD will get wiped out, which will affect to some degree
-All 3 companies definitely have some aces up their sleeves for GDC and E3. We'll have to wait to find out whose is bigger