I don't think that PS3 hw numbers are so important to third party developers to decide if putting their 2013 games on the Wii U or on the PS3. I think that the strong results of One Piece Mosous, Tales of Xillia and other games, as the ones I'm expecting from RE6, Yakuza 5 and Tales of Xillia2, will be way more important.
Also considering that Wii U will have zero install base compared to the 8.5 millions install base of PS3 (with those software results clearly underlining an activa user base)
About Japanese support, we saw very few games announced up to now, but not only SQ10 (some Sega game as All star racing, Tekken from Namco, Tank tank from Bandai and so on). Why should I judge the actual Wii U support situation imagining non-existent titles? If (or if you prefer: when) they'll announce more games, we'll evaluate the situation and change our mind. Nothing is forbidding third parties to announce their games via Famitsu or individual conferences or other ways. And we also have clear sentences from some publisher that is not supporting the Wii U with its own already announced games (such as Konami for example, or Capcom).
With your point, I don't see any non first party publisher would want to make launch games for a new system since the previous gen hardware will always have the number advantage on the new system.
I see your point on Japanese third party support. In that regard, Wii U would have one of the worst launch ever because I don't think they even confirmed any titles would be available on launch day, not even any first party titles. I fully expect Wii U to launch with no games.