We can solve this with biometric systems. Consequently, our fingerprints, irises, voice patterns, etc. can replace the use of software/hardware wallets.
Here is how I imagine such a solution will work:
Link between two and three of your biometric characteristics to your wallet.
When you want to pay for a service, or receive money, authorize the transaction with the already linked biometrics.
There already exists crypto POS devices. And if they don't already have biometric scanners, that should be easy to incorporate. However, there should be a secure interface that will verify the user's biometrics, much like VISA and Mastercard do when we attempt to pay for products and services online, to ensure protection.
The hurdle to this suggestion is that it strips off the layer of anonymity that cryptocurrencies are renowned for, as your biometrics essentially identify you. But without a hardware or software wallet, I don't see how that can be helped.