As, personally, a fan of contactless payments and no signatures, if adoption is fairly high for the Apple Card, it might be just the thing to help push acceptance of those along.
OTOH, I can see a bunch of people simply assuming that AP won't work at any drive through or sit-down restaurant and always opting for the physical card, which might not help adoption at those. Those two categories seem to be the biggest omissions now, IMO (and gas pumps, too, but at least you can usually go inside to pay if you want to use NFC).