The issue with that being would be SAO wouldn't be how it is now due to the many different genre worlds that are with the virtual world.
What they should have done was just stick to the first SAO world and not change at all. They could have made the shows a lot longer, instead of ending Aincrad off by killing Kayaba.
Akame ga killl on the other hand is a nice anime, I have watched all the current episodes and only read some of the manga.
You could make it time periods or different countries or different dimensions. Each could add a lot of depth to the series that it currently does not have.
Aincraid itself was still shit.
I'm getting the feeling that no one else has seen "floor climb" series before, because aincraid was done just as poorly as alfheim and had just as many plotholes and bad characters.
Not to be "that guy" but SAO was pretty much a video game reskin of druaga/.hack. Even if you stuck in Aincraid you'd still have the harem shit, still have no good male characters outside of Klein's cameo, and the villains motives would still be so utterly pathetic.
Just sayin, don't think staying in Aincraid would save SAO. What they should have done was just end it on Aincraid. There is no story whatsoever after it.