I am sure only minor part of strategies need enhancement over the time and the basics are always same and you could definitely stick with them even after 100 years from here.
Probably if we need a new trading strategy for year then definitely we will go run out of them because there are only very few effective trading strategies are available and most others are just supportive things hence you cannot use them for decision making.
Still, I am aware of the fact that trading strategies are getting old which means inefficient for profit making. But, when traders are finding their existing strategies are inefficient then they go fine-tuning it with respect to market's latest conditions but I am seeing really they are switching over to new strategy.