It doesn't matter if they will allow the existence of cryptocurrency or not but they can't do anything to harm it. They have done their worst and have seen that its impossible to ban it. For the Banks to join the race into digital currency will make the journey of Bitcoin move even faster than we think. Let them join the movement before its too late for them, for them creating their own coins will further create more eye openings to customers of their dubious act during the era of fiats.
They've already harmed it through regulations and by letting some abusive stuff happen "thanks to" them. It's never late for
them, they already have a strategy put in place and it already works by slowly pushing laws that go in contradiction with Satoshi's ideas and vision.
They'll "join the movement" by falsely advertising digital currencies on Blockchain as if they're Bitcoin, fooling most people into believing they're entering a new,
"better", revolutionary financial change on a decentralized network when instead they'll only join a more privacy-stripping currency than what we currently have today.