The Earth's crust contains 0.1% phosphorus by mass. It’s not going to run out, at worst it’s going to cost more to extract. Granted paying more than $425/ton might have an impact on food prices, but it’s currently a very low fraction of food prices. About 20% of overall fertilizer costs.

https://en.m.wikipedia.org/wiki/Phosphorus, https://farmdocdaily.illinois.edu/2017/07/fertilizer-costs-i...