As for me, banks don't see blockchain as a treat anymore but a pathway to successful and instant transactions. The collaboration of the blockchain technology and the banking system is actually beneficial for both parties. I believe that if more people will be aware of crypto, more banks would still adopt it in the future
Banks may see crypto just a faster mean of transferring money but they cannot ignore its potential of increasing their wealth as well. If banks themselves are holding bitcoin or even they are offering customers trading with clients crypto and taking certain portion of profit, I dont think so this will cause any economic loss to banks. In short, banks joined with cryptos can change the whole world economy and make it more stable.
Bank can transfer faster but not the same with how faster using bitcoin and altcoin, if bank adopting with blockchain technology we can transfer money to other country just few second, if using bank transfer we need more than one day for receiving money to other country, but not possible if bank want to adopt blockchain technology because bitcoin and altcoin not have stable coin price.