Like I said above I can't wait for something like this to happen from Apple.
Yes card terminals are everywhere but 'contactless payment' terminals are VERY slowly replacing them. Just imagine not having to carry a wallet. No store cards, no credit cards, no debit cards.
Hell, in a perfect implementation no ID. Just wave your phone over a scanner (police, airport etc.) and authenticate with TouchID. No need to carry anything else.
That would be the opposite to redundant. Carrying cards would be redundant if mobile Oses could crack this problem with a clean implementation.
Obviously problems too - what if your battery dies for example, or your TouchID sensor breaks...
EDIT - I guess if the TouchID sensor breaks it could always revert to a pre-set password like it does today for iTunes Store purchases.
You typically have other things in a wallet as well, including cash sometimes. There is also a security issue, both in terms of losing the phone, and potential hacking since the phone is often connected to the internet. I prefer to have these things separate. A lot of innovation is engineering driven without regards to actual benefits, it's more an attitude of; just because it's possible, let's do it.