I agree - I would not expect to see the D800 have a lower price because of anything Sony or Canon releases. But we have seen some price reduction and promotional discounts on the D800. It's been out for 18 months and is at that stage when the price starts to drop a little.
There are a lot of differences between Sony's new release and the D800. Just the sensor and mirrorless design fail to tell the whole story. But it is an interesting development and part of a trend to mirrorless.