They won't need the capacity with all the customers they are going to lose over this.
I wonder how many will actually leave. If customers have been totally satisfied thus far, if Dreamhost makes it up to them they might actually stay.
One thing to learn about this is to NEVER use your debit card for purchasing. You might say, "Wait but isn't that what all the marketing is about, using debit cards to purchase items and have it directly come out of your checking account". In fact, that's the problem. Do you really want a merchant to have direct access to any funds in your bank accounts?
With a credit card, the most a rogue merchant(or thief) can do is max out your credit line, maybe even go over it but you can dispute the charges and not be out a thing and be little effected. However, if someone overcharges you on your debit card, you could start bouncing checks and be potentially wiped out.