There was some discussion on Hive about removing author and curation rewards paid out in HIVE during the darkest hours of the bear market that we seem to finally have left behind. But that discussion hasn't completely died down, yet.
I think it should be abundantly clear that suggestions like that can only come from panic over abysmal HIVE price action or sheer greed.
The Achilles heel of DPoS systems is the centralization of stake. If the only rewards paid out were witness rewards and perhaps the tiny 3% HP holder's reward, control over the chain would become firmly entrenched into the hands of the current group of top 20 witnesses.
The only situation in which it would not cause significant harm to reduce the inflation of HIVE by removing PoB rewards would be one where dozens or more tribes have become major centers of wealth through their own successful tokenomics and thus motivated to purchase large stakes to secure a place among the top 20 witnesses. With witness rewards dwarfing other sources of inflation, merely maintaining the same degree of power over governance over time would cost actual money. That might tempt popular and high-value tribes to fork Hive to create their own blockchain.
I would say the idea of removing PoB HIVE rewards would be very short-sighted.