Prohibitively expensive is all relative. Pre-Fable, I was getting fine on the 5x plan for 1-2 concurrent long-running tasks plus interactive work (I do a lot of coding for work, but it is not my full work day). I don’t think a cache miss every hour on Opus hurts that much, even at 500-600k context. It would be nice if they got /clear working on remote-control.