If COD is the main prize in this deal (which it is), pretty sure purposely blocking COD and any other big console Activision game like Diablo would only drive more people to Xbox.
The best thing for Sony to do is hum along the current marketing deal they got in place (I think it's for 2 more years), and get MS to agree to a deal where COD is still on PS. Pretty sure MS was willing to deal and offer Sony a terms of length deal. But Jim Ryan brushed it off. Well, see if it can be back on the table. But if MS says forget it and the cord is cut no matter what than that's too bad.
On the plus side, they got Bungie, and a ton of first party studios making GAAS games, in which at least a couple will be shooters.