I suspect the cryptocurrencies you will see more widespread use of by mom and pop will at least for a generation be USD and other fiat currencies. The reason is quite simple actually---human habit. This is something that takes generations to change.
As for the use of tether....not putting it down but it basically is not doing anything to make it better than other solutions (like paypal) without a blockchain to my knowledge. There is counterparty risk in using it as each token is simply an IOU.

If I am wrong please feel free to let me know more though :)