If we introduce a new PoS algorythm recalculating rewards, based not on time, but on actual staking, and decrease rewards, and there would be a higher PoW hashrate, than it would be more PoB rewards.
But POB can't be dominating, only it could dominate, if you burn most of the coins from supply, than yes, it could be truth.
But there is only about 15% supply burned for now.

If we burned like 90% coins than I could imagine that it could dominate. But it's impossible.