Certainly if they change the laws, then what is presently prohibited could be allowed. Of course, if the ECB was able to issue the digital currency to the public, then the commercial banks could become irrelevant. This was part of the motivation for the ECB putting out this information.
The ECB can create digital reserves for commercial banks. These reserves are considered a form of central bank money and can be used by banks to settle debts between themselves.
That is true but it doesnt enter the money supply. It is not legal tender but rather a bank instrument. The Fed does the same yet the only ones who are able to have reserves are those with master accounts (i.e. banks).
Insurance companies, hedge funds, or the local church cannot have them. Hence the Fed and ECB are not creating dollars are euros unless the reserves are converted by the commercial banks into banknotes (something that isnt going to happen since cash is a dying animal).