User blog comment:XxKiritoAsunaxX/Out of everyone's opinion/@comment-6697950-20141203214951

What exactly do you have in mind when saying "how long will it last for"? Are you asking how far the story goes, how long till the anime runs out of content or how long will the series itself be ongoing?

If you're asking for how long the series will be ongoing, then there are around 3-4 more volumes to be released for the main series (with around 2 volumes released per year) + a Progressive series spin off which may last until the 10th floor at the very least, with a pace of 1 floor/book (aside the first two floors) and a 1 book/year release date it could take 7 more years + more if the author decides to continue past the 10th floor. Then there's a new spin off series for Gun Gale Online which we can't even predict how long will last since the first volume is only coming out in a few days. Put it simply, SAO has the potential to continue for several more years at the very least.

If you're asking about the anime, I'm guessing they're going to need two seasons for the last arc. +2 years in between a season airing, if the anime is continued and the current pace is kept up, so around 6 years if it's decided to adapt the last arc.

If you're asking about the story itself, there's one last main arc that the anime hasn't adapted yet. It's the last arc that the author has written as a web novel, but it's still in the middle of being published. There are chances that the author might write a new arc though. And even if he doesn't, there's still the aforementioned Progressive series + latest spinoff.

As for your second question, there's no official MMO game in the works as far as I know.