DeeCee, I'm not talking about pages with old addresses being reinforced from outside. These are pages that have no current existence outside the minds of search engines.
If you go to the electronics store and meet a sign saying "We've Moved!" with a new addresss, you might absent-mindedly go back to the old location once or twice. But it wouldn't take you a year to update your address book. Wipe the old one, put up the new one.
And if you did revive dead pages, you would be linking to them yourself, or putting them on a current site map. No need for g### to "remember" the URL; it will be given a new one.