It's hard to tell. There is a possibility of a redesign of the case, which could cause the price to go up a little but probably won't unless it's something crazy.
If they change the base model to have more RAM than it does now, like they did when they updated to the 2009 model, that could cause the price to go up as well. The 2008 8-core model started with 2GB RAM and the 2009 8-core models starts with 6. When they updated, there was a $500 increase. And if you go buy RAM from Apple, which you should never do, they charge $500 for 4GB of RAM. So in that case, the price increase was caused by the RAM.
Many people want the base HDD to be 1TB instead of 640GB. This is a good possibility. However, this could cause the price to go up a little. If you were to build a custom MP, they would charge $100 extra for bumping up the HDD to 1TB.
Many people expect the GPU to change as well. The base being something like an NVIDIA 270, I'm not really sure about NVIDIA so correct me if that's wrong. As for the high end GPU, it is widely expected to be the ATI 5870. Now, with the change of GPUs, this could also change the price of the MP, however I personally do not expect it to.
Now there are a lot of people who think that if there will be a price increase, it will be because of the new CPUs. However, if you look
here, you will notice that the estimated price for the CPUs that are currently in the MPs are extremely close to that of the CPUs that will be in the new MP. The price difference between the 5550 and 5650 is only like $38, that's not a big deal at all. And the difference between the 5570 and the 5670 is only $54. Sure, the price of the old CPUs in the MP have gone down, but has the price of the MP gone down? Of course not. Apple is still selling the MP as if the xeon 5570 is still priced at $1386. So Apple could just put in a 5670 for each 5570, a 5650 for each 5550, and so on. If they did this, the price could easily stay the same. If they did go up because of the new CPUs, it would only be like $100.
So the price of the new MP has many variables and many unknowns. However, we do know that the new CPUs shouldn't cause a huge price increase, if any price increase at all. We will just have to wait and see.