You forget most important thing. Its pools, its not entities like companies.
If one pool will behave malicious to Bitcoin, everyone will leave it and go with their hash power to other pools.

One real concern is if someone has huge mining operation its easier for him to scale his operation and cut costs while small miners can't do that. Big miners will grow, small will stay small.
Similiar to small companies vs corporations (big companies). No easy way to do smth about it here.