The beauty of bitcoin is that anyone can create a new hard fork version any time given a little bit IT expertise, so it is just a matter of whether enough people will use that new version. And I think over 51% of hash power is enough to present the major consensus, because that is how bitcoin was designed: With over 51% of hash power, you essentially control the bitcoin network consensus. People will move to the new chain and dump their coins on the old chain to kill it in a few days

Of course any company can lead the develop of bitcoin, only one condition: They must step down if the majority of community request it. That's the only requirement any company can lead the code development, otherwise it is a hostile corporation take over and can be solved by a hard fork