Thanks for encouraging further decentralization! because now is the time to plant the seed and send the message.
Under the current system I believe we need a larger spread or distribution of tokens to improve decentralization. We can get started on this through the actions you pointed out above in your first 3 suggestions. But why would behavior change now.. Which leads me to believe a more progressive approach is needed, in exploring options such as limiting number of witness votes.
There's an opportunity now to make something really really great but I think it means some of the witnesses stepping out of their comfort zone.