The comments after that article highlight the most common problem with Internet debates on this subject. That is, most of the people arguing have no practical experience with what they are arguing about. And if they do, it is decades old experience. To give a rough analogy about why that matters, imagine someone whose last experience with a cell phone was in 1990, trying to argue why IPhones are better than Androids. The mission the A-10 was designed to support is as critical as ever and probably more so. But that is about the only thing that hasn't gone through several evolutions (revolutions?) of change since the A-10 was first designed. Weapon, sensor and communication technology have so radically altered the CAS environment since the mid-1970's, that to even bring up the threat environment of places like the 1980's Fulda Gap is to reveal you no longer understand the modern combat environment.
Ultimately, the most important measure of success of a CAS mission is that the enemy dies quickly, and no friendlies die in the process. The premier experts in all aspects of that mission is the USMC. IMO, examining their current approach to executing the CAS mission is probably more useful than reading anonymous internet comments.
Nobody else comes close.