The reality is a bit different.

The bank you mention is not the only one in Germany, there is another one that acted even before. The regulation to allow them was prepared for many months, perhaps a year.
And the truth is that they don't store and hold any bitcoin. They just make use of a 3rd party. In another word the customers will be using 2 middlemen to do something, they could easily do on their own and for cheaper.

hey didn't "realized the potential of Bitcoin", They realized the money they could make
The banks aren't really interested in Bitcoin, nor its technology. All that matters is profits. once there is no more they will remove that option as well.
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