While it might make good sense from a business standpoint to try to expand into that market,
Can the PG-era WWE succeed in japan that is famous for their hardcore style "japanese death" matches??
I don't see why not. The
VAST majority of the biggest stars in Japan haven't been involved in "death matches", nor are they very often employed by the biggest companies like New Japan or All Japan. Wrestlers like Antonio Inoki and Giant Baba frequently panned "death matches" and companies that relied on hardcore wrestling in general. If I'm not mistaken, Baba is credited for coining the term "garbage wrestling" when describing hardcore wrestling.
Frontier Martial-Arts Wrestling began operations in 1989 was essentially the ECW of Japan, though they went hardcore long before ECW did, and used hardcore matches as it's foundation, The International Wrestling Association of Japan started up in 1994 and that's the promotion where Mick Foley won the King of the Death Match tournament in 1995. Both companies went tits up with FMW folding in February 2002 and the IWA folding in 1996. Tatsukuni Asano revived the company in 2011, but did away with the hardcore/death match format. The last real bastion of the death match and hardcore wrestling in general is Combat Zone Wrestling, but the format hasn't made them a force in pro wrestling.
As for WWE expanding into Japan, I see no real reason why it can't work if Vince genuinely wants it to happen. I'm not saying that it'd work, but I'm pretty certain that it won't work if he decided to do it half assed. Some of what that would entail include the fact that he has to accept that Japanese audiences might not just embrace all of his own ideas and concepts the way he may hope they would, nor all of the guys he'd prefer. For instance, while Vince may personally prefer a top level star to have a certain height & weight minimum, he'd have to accept the fact that probably a good 75% of the biggest stars in Japan from the last 30 years have been right at, slightly over or well under the 200 pound mark. At some point down the line, perhaps when/if the WWE Network is available in Japan,
MAYBE they could go the route of creating an alternative WWE brand featuring Japanese wrestlers, if they chose to sign a good number of them, working the style Japanese fans prefer, call it
WWE Ronin or something along those lines, create championships, and broadcast weekly shows on the WWE Network.