What would the upsides of such a match be for AlphaGo?
How many matches with other computers did Deep Blue play after its victory over Kasparov? (zero)
How many world championships did Deep Blue win? (zero, it played one in 1995 and lost to Fritz)
How many people tought Deep Blue was the strongest computer in the world in 1996? (All of them, because IBM said so and conveniently forgot about the lost world championship)
Google has already said AlphaGo is much stronger than other programs. There's no point in playing a match then, is there?
How many matches with other computers did Deep Blue play after its victory over Kasparov? (zero)
How many world championships did Deep Blue win? (zero, it played one in 1995 and lost to Fritz)
How many people tought Deep Blue was the strongest computer in the world in 1996? (All of them, because IBM said so and conveniently forgot about the lost world championship)
Google has already said AlphaGo is much stronger than other programs. There's no point in playing a match then, is there?