This article seems to support my suggestion.
https://www.cryptocoinsnews.com/declining-profitability-for-...
Quoting the conclusion of the referenced paper:
"Each future halving of the Bitcoin block reward will narrow the range of profitable entry for new Bitcoin miners considerably. The stronger relative position of incumbents compared to that of new entrants supports further consolidation of Bitcoin mining. Consequently, the distributed Bitcoin ledger, the blockchain, may become more vulnerable to attack, and its trustless nature may ultimately even be destroyed."