[cptcobalt]

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.)

[DrBenCarson]

The overlap of the “cares about battery chemistry” and “purchases the lowest tier device” is probably close to 0

The C1 modem gets a line because Wall Street has seen that expense for a decade now, so this is a “win” for them. Battery chemistry is completely 3rd party, so they’ll claim the battery life improvement

[jerlam]

The C1 modem is also not a feature that users care about, other than the increased battery life (that Apple does advertise). In fact, there will be concerns that the modem isn't as good as the existing ones in some edge case.

Putting the new modem into the new "budget" phone reduces expectations so that the impact of any issues will be blunted. Only when all the problems have been ironed out, that will be when the mainstream iPhones will get the new modem.