Fees is so hypothetical problem. There is bigger problems called scaling and witnesses distribution. As tarmo888 said it's only 30 tps. And as you can see it's only 1 of 12 distributed witness.
I agree about the lack of witnesses decentralization, I think that is the main problem for some users to take it seriously, but at the same time it has had some benefits too, mainly that Obyte has been able to iterate so fast because of this, this probably gets more difficult as Obyte becomes more decentralized.
I don't agree with scaling problem. If less than 1TPS is used and it can do 30FPS, where is the scaling issue? It can do 4-5 times as Bitcoin and 2 times more than Ethereum. For short peak times, it can do 10 times TPS too.
I gave you solution to distribute the witnesses.
percentage fee
If the witness joins because of fees, on the platform where most transactions are currently made by witnesses then it is not the witness Obyte is looking for. The whole point how witnesses work is that they need to post transactions themselves too and spend fees doing so. Your idea is basically to substitute witness fees, but not others. Where would those funds come from? From distribution fund that could be distributed to actual users instead?