I enjoyed this article mostly because it explains there's at least *somewhere* in the US where interest in a mental sport overtook the interest in a physical sport--in a place usually known for caring about physical sports, no less. A bar.
The article also mentions "information asymmetry" (something we usually refer to as double-blind info around here) is a big part of the game's entertainment. That means each players knows something that the other doesn't. I very much agree that that's a source of great entertainment and you can see that exact same concept in my games Kongai and Yomi. And the reason I hit upon using that as a design tool is that it happens in fighting games too, it's just that the time-scale of the double-blind decisions is much shorter--just a fraction of a second. But that uncertainty of often having to make your move when you aren't exactly sure what the other guy did at just that moment is where a lot of the excitement of fighting games come from. StarCraft's double blind moments are much more prolonged, so there's longer to think about them and build suspense. Does he know the other guy is amassing a huge force just outside his base? When will he realize it??
That said, fighting games are practically made for spectating. You can see all the action on one screen (a wonderful property!), the matches are fast, fortunes change, and comebacks happen. Not having to cut from screen to screen like you do in a FPS or RTS makes for a smooth spectating experience. Furthermore, it's easy to "read" what's going on (a guy punched another guy several times and his lifebar went down) compared to all the unseen effects going on in WoW Arenas or Guild Wars. I've tried to spectate several type of games, but fighting games and RTS games have been the most watchable to me.
Maybe we'll see both genres (and other mental games, too) rise in prominence as spectator activities.