Determining the success of a UTXO fork is a fraught exercise. There is no agreed-upon standard for measuring adoption. Establishing the existence of genuine activity is therefore challenging to the say the least. The list of potential proxies is long: full blocks, a robust fee market, an elevated transaction volume, a high transaction count, to name a few. And, unhelpfully, given that forks are often competitive with the parent chain, and compete for scarce attention and resources, quantitative metrics which offer insight into the usage of a given chain are often targeted for spoofing or manipulation.
How concentrated is block formation in Bitcoin? Which mining pools are dominant, and how long have they held that position? Are major pools in a position to collude and censor transactions? Which miners should developers and key stakeholders engage with? How exposed is Bitcoin to potentially malicious miners? Are major pools reinforcing their dominant positions or is the industry becoming more competitive? (This was an issue covered by Ark Invest in mid 2018.)