That article is discussing problems the modern wow infrastructure doesn't have. For example, development on City of Heroes is completely irrelevant to WoW development yet the article is resting a lot on one developer's opinion that modern server code assumes shardless integration between realms. He details how they had to rewrite server code from scratch for that game to accommodate that shift in server tech. Blizzard, however, has always claimed they continue to use legacy implementation and that's at least one of the reasons they *can't* do server merges this late in wow's history. In order to react to the problem of dwindling populations, they developed tech like cross-realm, warmode, and most recently layering. Those are the systems they are having difficulty integrating the old code into--not least because most people don't want that crap in the game. Some of them are claimed to be short-lived in the early stages of Classic, but players are skeptical of their reassurances.