I'm really wondering how long the Crystal itself will last.  I can see a coming era where these fanciful but useless appendages are greeted with the same rolled eyes and heavy sighs (and ... bulldozers)  now reserved for the windowless Brutalist slabs so popular in the 60s/70s.  My guess is that as it ages it will become too costly to maintain, perhaps no more than a decade or two from now - to be replaced by a bare bones, but functional gallery similar to what the Crystal itself replaced?