... not resolved is the concentration of mining ... Will bitcoin mining continue to be a free market?
No. Another coin will replace bitcoin for some applications, which coin preserves decentrality. It will offer enhanced privacy features as well. It will take at least a year, more likely two or three, for a clear successor to differentiate itself from its competitors and establish a network adequate to the task. Centralization is not generally a concern for speculators, nor indeed for most currency applications; for other use-cases where it is an issue, bitcoin will move aside and another cryptocurrency will take its place.
You think bitcoin will crash then?
Only as it always does, as part of the hype cycle, only to rise another order of magnitude on the next cycle. I suspect BTC will still be gaining value long after I've moved into a privacy-enhanced successor coin.