Surely if both Albert (GeorgeVI) and David (Edward VIII) had both died, in that order, then Prince Henry, Duke of Gloucester (3rd son of George V) would have become King. And then his descendents.
But if Albert (George VI) was already dead when David (Edward VIII) died without issue, the accession to the throne would go to Henry Duke of Gloucester. Albert's children having been taken out of the line by Albert's death, with Edward VIII still on the throne. He then dies without issue, leaving Henry to succeed. (Albert never having been king).
when David/Edward abdicated the crown passed to Albert/George and the immediate succession to his 2 daughters, and Henry was third in line. had king george died while Elizabeth was still a minor, Henry would not have succeeded, but would have been regent until Elizabeth was old enough to be monarch.