Why you worry 8 months before for something who is not definitive,maybe it runs much more than that.Let's suppose it is true that Ethereum mining ends after 8 months,as soon as it happens many people will share their best settings for other mineable coins and we will come to know that.For the moment Ethereum is still the most profitable coin to be mined and even your Rx 6600 XT does 32-34 Mhsh for just 50 watt of power so it is better than mining any other coin in the long run.