I agree. A lack of demand is not the reason why I don't think the seats will be released.

If DL offered same day upgrades with PMUs or miles, I'd think very differently. But, as we all know, DL will send F (or BE) out empty and leave people in back with PMUs whose upgrades didn't clear the waitlist. It's a crap shoot whether someone in Rev Mgmt will release a seat, or two like OP needs. An insider might be able to clarify this, but I was always under the impression that a human, not a computer, pulled the trigger on upgrade availability.