I have experiencing buying and paying Cryptocurrency to my host and I bought a lot of stuff too on the internet using my Cryptocurrency it's tried and tested and proven to worked and this is what constitutes to the success of Cryptocurrency as payment options and I don't see any problem when it comes to adoption, altcoins also have a chance for adoption for payment, as long as the advancement in Cryptocurrency in payment the adoption will make a progress.
Paying by cryptocurrency coins is quite convenient. However, the only problem with cryptocurrency payment is that it isn't recognized widely nowadays. Furthermore, it only accepts some of the coins such as BTC, ETH,.. not other coins. Personally, I think crypto payment will need a while to be widely popular!