That means, I can come tomorrow and open up a 0% fee pool, sell my miner and disappear?
I guess the other pool owners do not share your view!
But a 0% fee pool may not be profitable if there are a very large member base. How much you earn in a pool is a function of your hash rate percentage to the entire pool.
There will still need to be new pools to open up to ensure that there are pools of varying hash rates and where members can find better yields even with higher pool fees.
You think to much.....

You think to smart.... ;-)
90% is free Hashrate.
Most of them are not so clever. (means not I am clever)
Or why stay so many people in 2% pool with most hashrate?