I just got off the phone with a Chase representative. He told me that they can't re-open the accounts. But he also assured me that because the accounts were closed due to lack of use (as opposed to delinquency or other reasons), they will show up on my credit report as having been closed at my request. He said that Chase's policy is that if an account is unused for 2 years, they will interpret that as a sign that the customer wants to close the account. So they treat it just as if the customer had written them and asked them to close the account.

I'm still a little bit worried about whether the phone rep is right about this. So I'm going to make a point of checking my credit reports in a month or two to make sure. But as long as what he said is correct, it sounds like this isn't really a problem for me at all.