There's not a comparison here. YGO actually did overtake MTG around the time it release Phantom Darkness. Can't say if it's still there but lol.

That's true... but companies succeeded. Kind of. For instance, when I was in Middle school (was it really 12 years ago?), Magic was overshadowed by the ever-yawn-able Pokemon. Several Years later, the same thing happened with the equally-dull Yu-gi-oh. How? By Expanding the target age market and via mass-bombardment of product. However, while these products were still successful, Magic never died. Not because those other products were better, but they were pointing at the wrong target audience. The people who played such card games grew up and moved on.

A company COULD overtake WoW, by targeting the pre-15 market, and be very successful. But it wouldn't be more than a flash in the pan, because WoW has the 16-45 year olds on lockdown... because it's diverse enough to appeal to all styles of people.

Part of the problem with that analogy is that 99% of the TCGs that were created to take on Magic were just really awful. They ran the gamut from way too complex (Middle Earth/Star Wars) to just plain weird (XXXenophile, anyone?). Of all the games that were released in the mid-90s glut, the only one that survived was Legend of the Five Rings, because it managed to be both a really good game and carve out a separate niche from Magic.

On the other hand, most of the MMOs that have been released to take on WoW have been pretty decent games that might have been very successful in a WoW-less world. At this point, there are just so many people playing WoW that any other game feels like a ghost town by comparison. And nobody wants to play a multiplayer game by themselves. Basically, WoW will remain top dog until it dies a natural death or Blizzard loses their mind and just totally destroys it. Even a game like Old Republic, which will have the benefits of being made by a well-liked developer and based on a popular property, probably can't beat it.

WoW is the game everyone plays because WoW is the game everyone plays.