Tencent doesn't have one of the major consoles nor the vast majority of desktop operating system installations. If someone was going to encourage the government to stop the merger I'd expect them to try defining the market along terms different from just "size of gaming revenues". They'd target more the synergies that could be used to anticompetitive advantage and limit customer choice.

Not to say that will happen. Just that if it does, it wouldn't be on dollar size in game sales alone.