It's already impossible to learn all of any area of mathematics and has been for at least a hundred years (probably 150+). If you drill down into the detail, you'll find that the "world expert in X" is actually somebody who is very knowledgeable about X and, particularly, the sub-field X.Y and maybe, just maybe, knows everything that is known today about the specific area X.Y.Z. But even that can't be quite true since, if any other person in the world is working on X.Y.Z, then that person knows all the stuff they invented this week and haven't had chance to write a paper about and, unless he's telepathic, our world expert doesn't know those things.
But that doesn't mean that "learning mathematics" becomes impossible. The maths we learn today in schools and universities will still be perfectly valid in a thousand years' time so, as an absolute worst-case, you could still teach a math class in 3014 by pretending that nothing new had been learnt in the preceding millenium. The only real problem with that approach is that our selection of topics in 2014 might not be relevant to 3014. For example, there's a tendency to include more discrete mathematics in school syllabi at the moment, presumably because of its applicability to computer science. Who knows, maybe in a thousand years' time, there'll be some killer application of group theory that means we teach much more of that and much less calculus at high-school level.
do you think it will ever become impossible for a beginner to learn all the known material on a subject (such as mechanics), simply because there is so much prerequisite material to learn?
If you look closely at this question, you'll see that it already contains its own answer. It's already impossible to learn all of mechanics, precisely because there's so much of it and there are so many prerequisites. This means we'll never run out of basic mathematics to teach schoolchildren. If you want to teach kids wormhole hypermechanics but you can't because of all the background they'd need, you teach them that background, instead, and use the wormholes to motivate it.
is there a point where to discover something new, one must spend more that a lifetime learning what is already known?
(even in a very narrow field) – njzk2 Nov 24 '14 at 21:45