To ensure some sort of centralisation never happen, the best way is still to spread the hashrate concentration to multiple new pools. I guess since there is more and more people coming into the game, and a lot more will come I think because of the price rise, actions will never have to be taken.
i think it eill not possible to ne centralized since bitcoin smart contract can't be modified anymore its was maxd fixed as is. if ever they are planning to centralized maybe tjey well release a new coin or new bitcoin update representing new coin.