That's a good write-up of how the difficulty adjustment works!

The difficulty adjustment offsets ASIC efficiency gains though, was my point. So it doesn't matter at which level of efficiency the average ASIC is. The difficulty adjustment just counter-balances to make things harder. The available electricity to mining will be used up regardless of the hashrate.

The only significant thing with efficiency is that investing in more expensive and efficient ASICs gives a mining operation a temporary edge over the competition, until that level of hardware becomes a commodity.

Please let me know if I'm overlooking something.