I remember playing GTA: San Andreas, riding around in the country on my racing bike, hitting the hills of San Fierro, getting lost in the desert, before going back to Los Santos for a few gang wars. It seemed really big and epic, and I thought there was no way any GTA was going to top this one. Ever. And behold, now in GTA4, it's going back to one city. A no doubt much more detailed city, but still just one city. I was really disappointed when I heard that, because I loved the diversity in the areas in SA. It looks like I was right.
Of course, the scope of SA will be topped eventually. In 2050, when we're able to render the ever-changingplanet in ultra hi-def, and Carl Vercetti Bellic the 28th will be able to enter every house and building, and will be able to ally with the Mafia, the gangs, the military, or the International Housewives Union. Then, I'm pretty sure we'll see more diversity, and more stuff to do. Gee, I can't wait to circumnavigate the globe with the wholeplanet's armed forces after me!
With a game like GTA, there's always room for improvement, because you can always add more.
Which brings me to my original question: How can Galaxy be topped? How do you add more, when Mario's explored the corners of the universe, and has conquered gravity, the ultimate foe of the platformer? What scheme can Bowser now have up his sleeve, now that the creation of a dominant galaxy in the center of the universe has failed? (Oops, teh spoilers. I'm terribly sorry. :P)
Perhaps in 2165, when VR has been mastered and gaming has been born again, the cycle leads again to this very spot. After the flop that was Ultra Reality Mario Cleaning Things With A Backpack, Shigeru Miyamoto IV needs a game to restore faith in his great-grandfather's creation. Now he has his chance, with Nintendo's new system, the Fiil, which revolutionizes VR by adding the sense of touch. He'll create Ultra Reality Mario Universe, which will take us on a journey through the universe as Mario, defying gravity and orbiting worlds just as our ancestors did years ago with their now-primitive magic wands.
...So I guess it'll be a while. In the meantime, who's up for Sunshine 2? :D