I think the Ring champion is also fairly rated now. That is as good as a 5th belt already.

The Ring magazine has the right idea and they don't charge any fees to win their belts, they at least try and be impartial.

Unifying titles is as hard as ever now, often you'll need to vacate one organisation to win in another.

Also, the only people that care about belts are the lesser fighters. The biggest names aren't even bothered with them now, they know the fight makes money with or without a world title.