XSEED teasing yet another thing to be revealed TOMORROW!

If it's Way of the Samurai 4, I wouldn't have to preorder the European version. That'd be swell.

iirc, WotS4 has stealth. I doubt it's of the same quality of Tenchu 4 or Shinobido, but if there're hints relating to stealth, it'd fit with WotS4.
According to the wiki there are Tenchu like assassination missions
I've never played a Way of the Samurai game before, but if Xseed put this out at retail I would preorder it. They are currently having the best year they've ever had, no matter what they may have not put out or what's been released as DD only.

It's all obviously an attempt to raise money to justify releasing the rest of the Trails trilogy at PSP UMD retail. :p