It is still not the crypto-to-crypto transaction guys. Bitpay is still in the middle so there is a cost in the middle. If this is a crypto-to-crypto transaction then I would say that this is really a big news. But for AT&T to have someone in the middle to process the service then this could be considered as 'half-baked', in my opinion.
But honestly, this is the way bitcoin payments are going to be done. Companies are not going to hold a volatile asset as a means of payment/revenue, doesn't matter if the asset is going up. They simply aren't going to hold a volatile currency. There will always be a middle man for bitcoin payments for 99.9% of companies.
I have a thread on here where I point out this will actually hurt the bitcoin price because every bitcoin that gets spent by someone isn't just moving to a merchant, instead it is being immediately sold on the market, creating downward pressure on the price. Of course to balance this, merchant adoption means it is more likely more people will own bitcoin in the first place, but the immediate effect of spending bitcoin will be the same as if you sold it because companies are always going to use services like bitpay. They have balance sheets in USD or whatever national currency, which means they need to square up revenue in fiat not in crypto.
The rare exception would be something like Overstock where the CEO wants to move it to being a blockchain company and it actively invests in bitcoin by keeping some of the bitcoin payments it receives in bitcoin rather than converting all immediately to fiat. Don't expect direct adoption of bitcoin by most merchants, it just doesn't make sense for them in terms of risk or accounting. It is one thing for a company to invest in something using funds they've set aside for investments, but companies aren't going to put their direct revenue up to the whims of the market after receiving that revenue from the customer.
The important thing is that large companies are starting to accept bitcoin. The Spedn app apparently works with multiple large retailers, and now AT&T accepts bitcoin as well. All of a sudden now in 2019 numerous major companies accept bitcoin payments, that is HUGE! Though I still think Amazon is the big fish we are waiting on, given that is it the central hub for buying things on the internet for a significant part of the world. But already we can now have an answer to people when they say "where can you even spend it", we can now list a number of large well known companies that accept bitcoin, and that list will only continue to grow!