In terms of loaning the card - you could just add your card to your wife's wallet on her phone.
I'm suspecting Apple will have device transfers of funds soon - when that happens, you'll be able to more easily give funds to the kids or babysitter (hopefully a little easier than e-mailing funds today). Me, I'd like them to give the option to tap iPhones / Apple Watches to transfer funds.
Canadians won't see the device fund transfers anytime soon. I'd be shocked if we got that update when Apple rolls it out. It'd be nice though lol.