Bethesda seemingly had no issues buying out Tango Gameworks.You don't see American publishers successfully buying out Eastern studios for a reason.
If you're a AAA game developer in Japan, your game is not going to be played by a majority of the Japanese gaming market unless it's on the Switch or something. The global market is what really matters nowdays due to the Japanese games market atrophying so much. At this point, if you want to make big budget games in Japan, your best option is to hope someone like Sony or Microsoft or Nintendo or *whispers* Google is willing to throw large amounts of money at you.With Japanese culture, hard to imagine a studio of talented employees willing to make games that never get played by Japanese people.