It probably won't go on forever, but at this point there's three years of the trend and only a small fraction of the globe has even heard of bitcoin. Would be surprised if network hashrate didn't grow like it has been for the foreseeable future.
Similarly, BitCoin isn't going to be able to continue advancing at this rate when the problem of accelerating BitCoin computation reaches the point where it is reducible to the problem of accelerating transistors in general.