Bitcoin mining will become less centralized in the coming years because the technology has hit the wall of Moore's Law.

Until recently, every innovation increased the mining efficiency by 100 to 1000%, every few months. Before you could get your rig, new tech would come out that would be up to 1000% more efficient. Then when ASIC chips came out, china had a huge advantage because they produce silicon and making the chips in china eliminated silicon distribution costs, especially time.

Now the technology has hit Moore's Law, so the performance will double about every 18 months, making it a far more equal playing field worldwide in the coming years.