one thing has nothing to do with the other. segwit won't stop miner centralization. I don't know why some people think it will.
but don't worry, its not a 'handful of Chinese guys'... look at antpool, there's almost 100k workers in it. and that's just one pool.
firstly pools do not have ultimate control.
its a symbiotic relationship between pools and nodes.
yes pools can collate data in new ways and re-invent a blockstructure, but if the nodes do not accept it. then the blocks get ignored.
even if a pool had 50billion exahash. if the block doesnt propagate and get accepted by nodes. then its just wasting pools time. because all the merchants have trashed that block in 3 seconds.
knowing they cant spend rewards for 100 confirms they wont do funky blocks in the morning unless they know the block would still exist and have 100 confirms (blocks accepted ontop) that are viewable from merchants nodes in the afternoon to be able to spend that mornings block reward.
everyone has already seen that blocks that dont fit the nodes rules get rejected in just 3 seconds. and pools then realise their mistake and the very next block they make are blocks that fit the rules.
every week we see pools making blocks either by mistake or intentionally that dont fit the rules. and within seconds or a couple blocks (rarely) pools learn their lesson and ensure their block fits the rules of the majority of nodes
https://blockchain.info/orphaned-blocksbecause its not just about the cost of creating a block (electric+time) its also about who has a node that would see their funky block to spend the reward with in 100 blocks+ time.
EG
you might see for instance 80 merchants have a node that would accept it.. but if that pool wants to spend the reward with the 800 other merchant nodes who wont see the block. then there is no point making a block that wont get seen
Seriously? It doesn't matter how many "workers" are in a pool, most pools are controlled by 1 dude and Antpool is controlled by Jihan Wu (1 dude).
I'm glad you think miner centralization is a problem,
location is not much of an issue. you will be surprised that for instance antpool is not located in one location, but dozens.
even pools claimed as being "chinese" are managed by people that are not in china. (slush is managed in thailand) and ontop of this pools have many stratums spread out around the world. so if one stratum is shut down. in 2 seconds the farms are 'pool hopped' to another stratum else where.
lastly thinking that one guy has 70% control of pools is an utter laugh that no one can prove using real statistics. but only unbacked whispers from twitter and reddit.