This kind of storing has been popping up a fair bit recently. I don't really see how it's news.
Watson made the Test team because he was in the squad for his versatility - as a player who could fill any position that needed filling. It just happened that he was chosen to replace an opener. I will admit that his batting performance since then was better than I expected. I am still not convinced he should be called an "all-rounder", but leaving that aside, he has easily confirmed his ability as a fill-in Test batsman, and earned consideration for an ongoing place in the lineup.
However, the idea that he is one of the two best choices for opener is a bit weird. Apart from all the hoopla about Hughes, there are at least two other openers who should be consdered at number 1 before Watson, and that's only considering those with Test experience. The most obvious response to Watson's recent performance is to compare him with other middle-order contenders.