There is a very simple and elegant way to solve this problem. You need to enter a minimum fee amount.
It is a very lazy solution that only causes more problems than it solves.
For starters what would the minimum fee value be? Lets say the coin is worth $0.01 you hardcode the minimum to be 0.01X (X is the coin). Now price goes up to $10 and the minimum fee of that coin is suddenly 10 times more at $0.1, then it goes up to $100 and fee reaches $1 and so on.
Your solution simply added mandated hard forks each time there is a big price rise to reduce the minimum fee.