You can always create debt. That's all yield is. It's the rent on money loaned and you can definitely have it with a fixed supply.

It just means that you'll get recked faster because you can't devalue your debt... Unless you're an ecash fool that wants to create mints. 

Then your back to the same shitcoin universe with mints creating more ecash than they hold in sats. Like a dog back to his vomit.