After endodonics are completed, even if the did have to remove most of the crown above the gum line, they could do a direct resin post and core, which is then cast in gold, and which is essentially a cast metal part that goes down into the tooth/roots some, and has metal now above the gum line on which they could cut a preparation and cement a crown. (that sentence has way too many commas but you get the idea) The tooth while dead, is actually ankalosed in place, making about the same as a metal implant in that spot.