iPad battery

Assuming improved iPads are released over time, doesn't this (that Apple will just ship a new machine rather than actually replace the battery) mean iPads are expected to drop in price significantly (or, extremely unlikely, that Apple will somehow keep a large inventory of obsolete iPads)?  Otherwise, each time there is a new version, owners will suddenly "discover" that their iPads no longer hold a charge and require an exchange (which, naturally, will mean the new version of the machine as the old ones disappear).  I'd recommend waiting a few months to clear out the refurbs and old inventory before trying this gambit...