Interesting! The self-appointed editors of Wikipedia move fast!
Something I've noticed is that the version of the clause in the RCID agreement goes much further than the version described in the Wikipedia article and the piece shared earlier by
@Chi84. The RCID agreement gives the timeframe as "(21) years after the death of the
last survivor of the descendants of King Charles III" (emphasis added), whereas the usual form of the clause refers to the last living descendent alive at the time of the document's drafting. Does anyone know if the RCID version, which could in practice mean forever, is an accepted variant?