6x RX470 8GB with 1500$ this means a cheap RIG. Without the reduction to 2ETH/block this should make around 4.5 ETH/year that sounds good for me but with this changes....duno.
Why they don't do it ASIC resistant?
Whoa. $1500 for 6x RX 470s, even if they are 8GB, is NOT cheap at all. Old GPUs like the 470 are now being sold at bargain prices of around $100-$120 where I am right now. If you really want to risk losing all your money then I suggest you do more research and find cheaper rigs.
Wrt to ASIC resistance, it's not gonna happen because the ETH devs have already decided.