Not only can economic growth and technological progress slow down. They can stop and reverse. Just because we're now further out in front than humanity has ever been before in history does not mean that we can't go backwards. Economic growth is probably more likely to reverse than technological progress. That's what a depression is, after all.

But a sufficiently bad global catastrophe, perhaps one that destroyed the electrical grid and other key infrastructure, could reverse a lot of technological progress too and perhaps knock us way back without necessarily causing complete extinction.