I agree it's unlikely, but that's the sort of sales the PS4 needs eventually to be able to sustain itself as a platform. If people aren't moving over, then it will continue to hold publishers back from committing to current-gen for anything other than games which require the highest technical specs. Since we're talking about Japan, there aren't many of those!
If DQH ends up selling 500-600k on PS3 and 200k on PS4, and MGS5 does the same, that is unfortunately not a very encouraging outlook. The important thing about these few months in Japan is that there are a lot of PS4 titles including Bloodborne, and there are more on the horizon. If people don't jump on right now, then it's likely that there won't be another big window of excitement for a while, maybe not until the end of this year or early next year.