No, I mean like if crate series #2 comes out. #1 will stop dropping right? So if you have one of series 1, the prices will go up?
For TF2 crates, the majority never go up in price. There are a few exceptions where a particular crate contains a more valuable, highly sought after item that would make it worth more. For example, Crate Series #19 has a chance of dropping a Strange Grenade Launcher (in addition to the chance of dropping an Unusual hat), which is worth around $6 in keys. Even then, that crate only sells for around 1 key/$2.
Crate Series #1 in TF2 sells for around 1 key/$2, and it's mostly because it has a chance of dropping black/white paint which sell for around 1 key/$2. Also, perhaps for the novelty for being #1. It used to be cheaper, but it's taken 3 years for it to crawl up to the price it is now.
The prices of the current weapon cases are likely the highest they will ever be. There's always a possibility they'll go back up in price, but even then, you'll be waiting many years for that to happen.