Again, managed expectations for a Yakuza game would be a few hundred. There is very big doubt it would sell well. As pointed out in an earlier thread this is a series that can't even beat The Wonderful 101.
Obviously goes without saying but supporting the digital titles will be paramount to any chance of Zero. I'll probably buy Yakuza 4 digital even though I have it physical. Call it a backup copy and an excuse to support the series.
Numbers?