When the price for a Bitcoin is 1 Mio USD we still can keep the 1 Sat= 1 USD cent, but since fees are calculated in sat/b, fees will get absurdily high or am I wrong here?
Your calculation sounds about right. But.. well, the miners have to earn something too. And it would be normal that at the point 1 BTC = $1M LN would be properly up & running & widely used. Yes, this means that although we'd love the high price, it may not come
that early.
The point is that yes, at some point the fees will become prohibitive, but at that point one would no longer use on-chain transactions for withdrawing from faucets and buying a coffee.