Like I said this is going to end badly, I have never heard of a merger that has gone of smoothly without customers loosing out in the end. No matter what the "economic" necessities of cutting overlapping jobs people are gonna get fired and this is going to affect the morale of both companies. And this is only a minor effect. Who decides who goes and who stays?
Like someone already said Im pretty sure Blizzard will probably retain all of its employees but they will be assigned aditional workloads (Activision Customer Support, etc. etc.) this cant work out well. Mergers serve to make money for the top brass, and sure they will make a heap, but in the long term Blizzard customers will lose out, the quality of titles will drop and in the end all that will be left is the brand.
I have a nifty blue line!