Private block chains are a big yawn, because they break the trustless property of block chains (if you don't understand that, then you shouldn't be investing in anything until you finish a crypto 101 course):
most core crypto concepts are lost on this alt crowd.
gotta love when crypto goes from being an alternative to the greedy bankers of the world, too working for them

study evolution and learn some history. how do things change? life didn't evolve from amoeba to humans in one go!
having japanese banks assimilate the 'idea' of a shared ledger (even if permissioned) is a stepping stone to decentralised finance. once they start using blockchains they won't go back, and when they fail the 'concept' of blockchains is already established and moving to open shared ledgers is easier.
do you expect banks to accept bitcoin straight off the bat?
do you expect banks to roll-over and die?
bollocks ... they'll evolve