Banks will never support Bitcoins, BUT, banks will in time develop their own cryptocurrencies.
Imagine Bank of England making it's own crypto currency, and BACKING it up with sterling pounds. Then you will see the bitcoin prize go to 0.
Bitcoin price will not go to the zero level because bitcoin has very big speculative value for Ponzi speculators.
Those are mostly derivatives surrounding it. Bitcoin itself isn't exactly a pure Ponzi.
By the way the investments into hashing hardware will still exist, such things cannot become valueless over night.