I think you misunderstand the current system. There is a 5% fee right now (unless set specifically lower by the the person/bot listing something). If the sale happens on the Splinterlands market, the set fee goes to Splinterlands. If the sale happens on a 3rd party market, Splinterlands is getting 0% and the fee goes to the market where the sale took place.
This proposal does not change that, it just proposes to set the fee to a fixed 6% from which 2% are burned.
So Splinterlands get only 4% instead of (at the moment) 5% and I think they fund tournaments with the fees, so we can expect that they will reduce tournament-prices by 20% or I am wrong ?