If one type of nodes, Classic for example, controls over 51% of hash power, they can implement whatever change they like by simply use this soft fork trick: Let all the old Core nodes accept their new format blocks while Classic nodes will reject Core blocks, so that Core blocks all get orphaned due to less hash power
This is nothing but a classic 51% attack by cooperating miners, and has nothing whatsoever to do with soft forks. If you manage to control 51% of the hashpower, you can ignore everyone else and always have the best chain. Bitcoin 101.
This. I hope it never comes so far