The old Flybe was granted grandfathering rights for the Heathrow slots last summer but as they've now lost the license I think the slots will also disappear. As far as I know, the new airline did not have any rights to those slots. They were awarded to an airline which, legally, still had an operating license until yesterday. The CAA were assured no tickets would be sold until the appeal outcome was decided.
As Albert Hall says, it really is now that we will see the true intentions of the airline.