...etc. will be remembered 20 years from now?
Yes. I don't know about every single one of those, but some of them like COD are so extremely popular that they aren't going away anytime soon.
You also have to keep in mind these modern franchises are to kids today the equivalent of what Mario and Metroid and Contra and so on were to us back in the 80s-90s. Kids today who don't own Nintendo hardware don't know what these franchises are and it doesn't mean anything to them, just as Nintendo fans who grew up in the golden age probably don't give a crap about these new fangled games kids are playing.
So its all about the perspective of what you played when you grew up. Kids who are playing Assassin's Creed and COD today will remember them with nostalgia 20 years from now, even though by then there will be some new franchises which we can't even imagine yet. That's the way it goes.
But to get this unrelated discussion back on topic, what do you think would have happened back in the 80s-90s if Nintendo had the same casual centric attitude back then that they do today? What if the big pack in game for the NES wasn't Super Mario Bros. but instead some 8-bit equivalent of Wii Sports? What if instead of making Zelda Miyamoto made an 8-bit Wii Music? What if instead of Metroid there was 8-bit Wii Play? Those games could have been fun, but they aren't the same thing.
What you have to keep in mind is all these great Nintendo games which core gamers have nostalgia for were made way back then before Nintendo turned their focus to casuals. Had that focus been there back in those days none of those franchises would ever have been created, or they would have been far different and unrecognizable.
Would we have the same level of Nostalgia for these games if they were what we had grown up with? I don't know the answer to that. Its possible. But all I'm saying is what Nintendo is doing today in the present day is a far cry from what they did decades ago when I became a fan in the first place.
So let me ask you will Wii Sports, Wii Music, Wii Play, etc. be remembered fondly 20 years from now? Or will they be rejected as gimmicky tech demos? The kids who grew up on these games in the here and now are the only ones who will know the answer to that, but we will have to wait about 20 years to see how they and history judge these games. Personally I don't think they have the same long term appeal as Mario, Metroid, Zelda, etc. but we shall see.