It is not a sequential perfect information game. Information is imperfect, actions can be taken by both sides at the same time, there probably will be action limit per time/game frame and the network will have to determine not only its next move, but also manage time for calculating that move. It totally changes the challenge.
As far as I understand (and I am no expert at all), AlphaGo basically creates a heuristic of what move to play in a given situation (which heurisitic is created by playing against itself many, many times). Instead of trying to "break" the game, they just decided to simulate playing and results were good enough to outmatch humans, but we have no idea how close to the "perfect game" AlphaGo actually got.
But - whole input to a network is 19x19 array with 3 possible states per cell, plus maybe turn count and one bit for determining whose next move is. S2 network should process graphic stream (lets say 1280/720), needs spatial awareness(minimap), priority setting and computational resource management. And it has to be fast enough in the first place just to follow the game.
I'm not saying that won't happen (who predicted Go breakthrough?), but it at least seem like a much bigger challenge.