Interesting question! I don't know much about Forex brokers but let me give you one piece of my reflection re this subject. I do think such companies may succeed in adopting Holacracy because from my understanding Holacracy is neutral. These companies may, by using Holacracy, discover they have a purpose they just did not know... and also make even more money. All living beings, including Organizations, have got a purpose, what I like to call a *Raison d'Être*, and this just only because of their existence.
Sometimes I like to dream and imagine what could happen if all companies become aware of their evolutionary purpose... and align to it