There are estimates for a population of between 9 and 11 billion people in 2050, depending on where you look and how you calculate it - there are of course loads of factors, mainly to do with resources.
Food, for example, isn't distributed well amongst the 6 billion we do have (I don't even think there is enough for those 6b full stop, let alone distributing it evenly), but when has it ever been even? When has any resource been even?
I think we're fairly clever blobs of matter that can find solutions to problems, so the extinction of the human race might be a tad far-fetched, but then you could ask somebody else what humans would be like in 100 years and they'll say we'll be so different to what we are now that we might as well be a new or different race, so to speak. All depends how you look at it, I guess.
So we'll have to change some things, definitely, but I think we'll manage on the whole.