They'll need those clones because the fanbase basically treats "written by Toriyama" as the "this is canon" rule. When he's gone the entire universe will shatter into pieces if it comes from different authors and everyone will endlessly argue over what's real or not forever.
Toei Animation keeps Toriyama chained up in a basement somewhere and they already have several clones of him growing for when he kicks the bucket.
They'll need those clones because the fanbase basically treats "written by Toriyama" as the "this is canon" rule. When he's gone the entire universe will shatter into pieces if it comes from different authors and everyone will endlessly argue over what's real or not forever.