Reading
this thread a question comes up to my mind.
If in the future, you can pay with bitcoin almost everywhere, how are you going to pay? The safest way to store your coins is to use a hardware or paper wallet (properly created). But in order to pay for a coffee at the coffee shop you cant use it, unless you carry your laptop or tablet everywhere.
Using your mobile isnt safe. At least as safe as using hardware or paper wallets. So, how do you think it will be done? Transferring just small amounts to your mobile? Maybe hardware wallets will have a mobile version?
Hardware and paper wallet are the safest way to store coins but they are not ever safe as well. However, if bitcoin get mass adopted it won't be easy and safe to payment for a cup of coffee at the coffee shop using the mobile but with the help of crypto currency credit card and authy or Google authentication can be use for safe transaction.