Bitcoin is mother all crypto currencies. If you follow the flow bitcoin dominates the price of all other crypto currencies. U might see ETH price is $3k or $4K but BTC price for ETH didnt cross .0.08 BTC but in the last bull run it crossed .01 BTC so price is purely determined by bitcoin only!! Yep ETH has more use cases but that doesnt mean it can overtake bitcoin and BNB is still a baby 
if eth is maxing out at 0.08 .. then at the "difficulty bomb" detonation. when it changes to PoS ot will correct down to 0.00004
because PoS is going to go 2000x less than its PoW equivelent