Perhaps Stake need to consider to implement it in the near future although it does not give any guarantee that complains will not come. I still see some people complaining about withdrawal fee even though they are playing on a site with dynamic fee where they can choose the priority level of the fee. Both fixed fee and dynamic fee has its own advantage and disadvantage. Here, players needs to understand and check the system first and check how much is the latest fee on the site and on the average fee on the mempool. A site wont be able to give what is the best for all players because every player has their own preferences. As players, we need to know which coin and which fee is more suitable for us. Even if there is a sudden huge increase of the fee of bitcoin/eth when we play with btc/eth, there is other way to avoid it on Stake. That's by using dinabot to exchange our bitcoin to other coins or simply do not use btc/eth for gambling if we want to avoid high fee.