If kids of the upcoming generation don't find nostalgia with Cave Story I will surely weep.
But to be more realistic, it's probably going to be stuff like
Borderlands
Anything by Nintendo (Mario, Zelda, Kirby, etc.)
Halflife 2 & whatever episodes
Oblivion, Fallout 3, Fallout New Vegas, and pretty much everything by Bethesda
KOTOR 1 & 2, Jade Empire, Neverwinter Nights, and pretty much anything by Obsidian
Definitely the God of War series
Hell, maybe the Gears of War series
Definitely the Assassin's Creed series
Eh... maybe the Call of Duty: MWF schlock. I'm not going to like it, but you have to admit, it was popular enough that the kids of today are going to remember fondly when they get to our age(s). Lord help 'em.
Essentially, whatever was popular, but did something (at least once at the time) that was memorable. For example, Borderlands being highly stylized and having a shit-ton of weaponry, or Cave Story just being Cave Story.
Pretty much what defined 'Nostalgia' for us. Granted, with the obvious exceptions, I feel it won't be as creative and dynamic as ours was, when gaming was still new and concepts and technology were essentially being broken with every big new title in the 80s and 90s, but it will still be there for the games that deserved it - the games that pushed boundaries and set themselves apart - or even just created the trends that currently stagnate the industry (They had to be popular and innovative at some point to inspire their imitators, after all).
My hope is that whatever they remember with the same love and reverence as we do for our Pokemon Red & Blue Versions, Metal Gear, Mortal Kombat (the first 3-4), and whatever other classics, even the redundant CoD shit, they remember the best aspects of them and continue to promote the innovative parts of them that we with our own modern biases failed to pick up, so the creative spirit, even if not the image of those games pass themselves on like ours did.
Legacy through innovation and impact - the best way for a title to pass itself on.