One day banks will accept Bitcoin as medium of exchange and accept deposits from bitcoiners. As soon as the world powers accept it as medium of exchange.
I think it will take about a decade for banks to start having a large amount of bitcoin as reserves.
The "central bank of central banks" already allowed central banks to have up to 2% of their reserves in bitcoin.
That's a massive change in how banks work, and I can assume this will only expand over time.
Are you referring to the BIS decision? However, that will depend on the decision of each country's central bank. So far, leading central banks like the Fed, ECB, BOJ or BoE are still skeptical about bitcoin, they do not really support this idea. Just like the ECB has been outspoken in stating that they have no intention and do not support the idea of adding bitcoin to their bitcoin reserves.
It can be said that no central bank has supported this idea yet, so I don't think it will happen in the next decade. It will probably take longer.