It's not bitcoin itself they're interested in, it's underlying tech, the blockchain.
http://www.bloomberg.com/news/featu...tells-banks-the-blockchain-changes-everything
They aren't backing anything that doesn't benefit them in multiple ways.
http://www.zerohedge.com/news/2015-04-30/first-blythe-masters-now-goldman-investing-bitcoin
With digitization of $$ they will have ultimate control. With the click of a mouse, bail ins, no runs on banks possible, minimum withdrawals, instant ban on sending funds to destinations. Another click, you can't click.
https://www.linkedin.com/pulse/cash-policy-tool-interview-hon-dr-harald-malmgren-tavares