Many who already play go are of the first group, as they are least likely to be frightened by 'the worlds most complex board game'. And many have already come across go in their line of work, meaning we are much closer to the 'critical mass', if you will, of those in this group who might possibly be interested, at least compared to other groups of people (I am simplifying here).
Journalists and news channels most likely increased base awareness, and slightly change some negative go preconceptions borrowed from board games in general (making it seem a little, 'cool', 'futuristic' or similar), yet Alphago will likely get lost among the other stories over time, not necessarily drawing in people excepting great manual effort and strain on resources on go associations' part.
In other words, at least in the west, it increased the size of the pool and, minimally, the quality of the bait, but not the number of fishing rods available.
So we could only capitalise so much, and even then, finding the optimum strategy was a delicate balance.
Well, at least that's my current model of events.