Obviously, Sandy Bridge will feature quad core processors, but, less than a year and probably in mid-early-mid 2011, we are going to see Ivy Bridge which will make quad core processors a standard and will dramatically lower the price on quad cores. Additionally, 8 core processors will start gaining momentum and with the future 'shrink' and cooling improvements, it's possible an 8 core CPU can be crammed into a laptop as small as the MBP.
With Ivy Bridge expected to make more impact than Sandy Bridge and to reduce the price on more powerful processors, the MBP may not have a substantial upgrade this year as it is going to take a lot of resources and research/testing if you are going to 8 cores. Also, Ivy Bridge is going to come out pretty soon.