Imagine if every Bitcoin halving, prices would remain the same or lower than they were before.
This would turn out to be completely unsustainable for miners, resulting in decreased security of the Bitcoin blockchain.
You hit the nail on the head of why Proof of Work in it's current form is unsustainable.
Bitcoin literally has to double in price in March 2020 , just for the Miners current profit to be maintained.
Of which many are already in the hole , only being sustained by venture capitalists.