That's the question. We should consider the overhead cost of knowledge, and the possibility that we will see a logarithmic increase in knowledge instead of a linear one (or, that we will see a linear one given an exponential explosion in resources).

Much depends on how you measure knowledge. If you count "bits of information", that's still growing exponentially. If you count "number of distinctions or predictions you can make in the world", that probably isn't.

There is a critical relationship between GDP and the efficiency of science. Until 1970, the money we put into science increased exponentially. Economic growth comes (I believe) exclusively from advances in science and technology. In 1970, we hit the ceiling; fraction of GDP spent on science had grown exponentially until then, when it suddenly flattened, so that now resources spent on science grows only as fast as GDP grows. This should cause a slower growth of GDP, causing a slower increase in scientific results, etc. IIRC there's a threshold of scientific efficiency below which (theoretically) the area under the curve giving scientific results off to infinity is finite, and another threshold of efficiency above which (theoretically) the curve rises exponentially.