I can't imagine her being in this position next year. To win 4 in a row, then lose in the semis and then win 3 more in a row next year and be in position to win the 4th would be a ridiculous story.
The only way such a thing could happen is if Serena miraculously finds her form from 2012 Wimbledon/Olympics, but if she plays with so many nerves and serving problems as she did this year, I don't see it happening.
I do think she will win at least 1 slam next year.
It's just so hard to imagine how much longer Serena will be able to stay at the top of the game given her age...however, maybe Venus offers some glimpse. Venus is 15 months older (I think) and she still is able to play amazing tennis some of the time. Given Venus' medical condition, perhaps Serena will too be able to compete at the top level for at least about another 2 years.
Said all of that to say, that if Serena is in contention for winning the GS next year, that would be beyond, beyond amazing.