I think a fair few people will see it just because it's a big light action comedy being released in (here in Australia at least) school holidays, and it's something for the kids to do. That's a market that John Wick is not in competition for. On the Other Forum i frequent (completely non-RPG related), one guy went because he had an Amazon advance screening ticket, and really enjoyed it, and another is going with a bunch of friends who are D&D players even though he's not himself. There might be a surprisingly solid word of mouth factor on this one.
True. John Wick seems to be relatively big hit.