If we have less and less people, there will be less brain power to innovate while as far as I can tell the innovation is getting more and more difficult as we moving forward. Just imagine inventing the wheel was probably easier than inventing the combustion engine.
I have a feeling that the huge technological advancements of the 20th century happened because of the exponentially increasing population. Also having more advanced technology helped back the population growth too.
So I think if the shrinking population will cause technological stagnation on top of the constant hardship due to the proportionally increasing number of elderly who need support.