This to me, undersells Shadow of Mordor quite a bit.
Yeah, the Nemesis system is the best part of that game. It's also pretty much, that game. Games these days, good games (and bad) come out built around the slimmest of mechanics. The fact that Mordor came out with a mechanic that was excellent, that was actually rather relevant to the game, that was functional and that was new, is a pretty big achievement.
Obviously somebody at Monolith realized quite early on what made the game they were making good/special, and clearly tied as many elements of the gameplay, visuals and story around that system. It's an open world game where interaction with the world actually felt meaningful, and I can't remember the last time that happened (certainly, it wasn't this year).
I also disagree it won't be remembered. My guess is that this mechanic will be copy pasted onto open world games, and maybe other genres entirely, for the next decade to some extent, and that the Mordor-esque label will be used (I'm guessing someone will come up with a better label than me though).