If you wanted to trade on the growing likelihood that they'll be forced to cut fees, which companies will benefit the most? For example Match Inc. gets most of their revenue from Tinder, so any savings would go directly to their bottom line.
I would look for the ones that are ready to launch "the next Apple Store" which will compete directly with Apple and become #2 in market share of apps revenue in a few years. Those ones will be much more profitable to trade on.