Do signs point toward Apple adopting a unique, new cell chemistry for what will be their high-volume budget product for the next few years? It would have probably been a marketing line if so, similar to the C1 modem. A bigger battery doesn't imply new tech.
(Yes, the phone expensive now, but these SE-tier phones typically get discounts pretty quickly after release through carriers/non-apple retail; and then a bigger & formal sale price decrease when the next phone generation comes out.)
