Hey Chris! I see 2 things here.
I think this will make BTC price go to the moon as a combination of speculation and as part of the adoption in Japan.
I believe Japanese people will for sure start using it, the tax incentive will also help drive adoption.
With respect to the transaction fees, they need to be low and hope this will change soon. As for the time it takes to confirm, well, today Bitpay (I believe) takes the risk and both the merchant and the customer don't have to worry about it. Not sure if this will be the case in Japan. Having said that this will open the door to accepting other cryptocurrencies like Litecoin as you said.
Honestly I see this as great news!