That's a bit like someone 20 years ago saying "My only issue with Credit Cards is there will always be someone who doesn't take them. So the need to carry my checkbook will still happen. I don't want to be stuck in the middle of nowhere and the cab driver only accepts cash or checks."
I haven't carried a checkbook in 15 years. And I now keep one $20 bill tucked in my wallet, just in case. Otherwise I use my credit card for every transaction I make. Over time I think it's entirely plausible that phone based payments could become the norm, especially with the enhanced security of being fingerprint authenticated. There are even states that are experimenting with digital driver's licenses that can be loaded on a mobile device. I think it is entirely possible that the wallet will become a relic of the past. Likely some places will still take "old-fashioned" credit cards (just like you can still write a check at some stores), and certainly cash will be around for a while, but I think mobile payments will be the norm sooner than you think!