to my understanding if there is only one admin and his account gets cancelled, the page will be deleted.
I know this is true for the old groups.
You can add one or more administrators to a Facebook page. That means the administrator is not necessarily the owner of the page.
Should the account of the owner be removed, the page would be removed as well. If you have a page and the administrator does not exist anymore, your only way to get access is Facebook support.