I already watch the odd Dutch game.
Many of the world's best players play in Spain just now, but I don't like Spanish football, so I don't watch all that many La Liga matches.
I'm posing the question as, having not been alive at the point Maradona joined Napoli, I'm not really able to make a strong argument as to the level of popularity of Serie A before and after he joined or whether he was a key factor in any change.