Even though the Japan regulators might not be interested to approve a bitcoin ETF at the moment, but I believe if the USA government officials have decide to approve a bitcoin ETF, Japan will eventually launch a bitcoin ETF in their own country too, and I believe the chance for a bull market to return in the crypto-currencies trading market would be high.
ETFs will eventually be accepted in multiple different countries, nobody is waiting for others to do it first. they have other kind of concerns, not to mention that the ETF proposals were somewhat flawed for example when it comes to getting their price they were relying solely on one exchange. and some other issues that have been outlined before.