Buried deep in a Kyodo News business round-up from a few days ago comes this promising stat: Compared with last year's June to August period, shipments of local beer grew by 8.1 percent this year. The tally includes figures from "45 leading local brewers," with shipments reaching 2,005 kiloliters. The Big Five, meanwhile, gained just .7 percent. Kyodo, referencing information form Tokyo Shoko Research, attributes the increase in craft beer shipments to marketing, such as being active in events through the especially hot summer (article accessed here).
While this is a fairly narrow window of data, I think it can be seen as positive. I am not sure where the numbers are on a larger scale (that would be interesting to see), but perhaps it means a few top brewers are finding their niche, in terms of both quality and marketing.