The people with money in their bank account are not going to wait 10 years to withdraw it, so that's a moot point. If they wanted those funds to be locked in for so long there are much better vehicles they would have chosen.
Banks are predicated on the idea that a limited percentage of depositors are going to want their deposits at any given time.
Insinuating that all assets must be liquid enough for all deposits to be withdrawn simultaneously basically requires that the bank only hold cash, which makes the entire concept of a bank fall apart.
From what I read banks must always have funds than liabilities and must immediately liquidate if that isn't true. If someone pays me to hold onto a box of cash for them I should obviously have it available when they ask for it back.
We may use fiat instead of gold now but that doesn't mean a bank can float itself by hoping no one opens the box and breaks their superposition.
Gold itself is quite volatile, you would have the same issue even on the gold standard. It was in fact an extremely common problem on the gold standard.
A bank is expected to be able to float itself as long as a sufficiently low number of customers demand their money at any given time, a bank run will collapse a bank no matter what monetary standard you’re on.
