Very well said, powersurge! This is a right-to-repair issue, or something close to it; the notion that only a serial-number-blessed factory original battery that stores paisley electricity (none of that plaid electricity stuff!) can be fitted to a specific model LEAF is deplorable. A standards body should develop a specification of all the parameters concerned with battery pack operation, and work that into a standard interface for battery packs. We're already part way there with the charging standards; you don't (well, you shouldn't) have any problems connecting a CHAdeMO charging station to the battery of any Tesla, a LEAF, an iMiev (sp?), or a Soul, no matter the model year. And if a battery pack communicates its characteristics in sufficient detail, it should be possible for any vehicle to either make use of whatever potential that battery has, or (as in the case, for example, of a battery with inappropriate voltage) politely explain the incompatibility to the installer. If the LEAF had taken such a modular approach to its battery, it would be possible for an aftermarket future supplier to offer a lighter, solid-state 30kWh battery pack with proper thermal management that could be plugged into an older car.
There'd be no benefit to the vehicle manufacturer for meeting such a standard, of course, unless some large volume customer like the US postal service came along and said "we'll order 50K EV delivery carriers from you if they support the SAEnum-de-num-point-num battery interface".