All calculations highlighted there assume fixed price, which we all know price moves, but good exercise to make a general point. I think the their original argument was to make ethereum 'more rare' by artificially changing the stream of inflation to a trickle per se, kinda like bitcoin halving mechanism.

That being said, they need to be more concise on the plan, because going about it the way they are right now where the difficult bomb had an intention/use/function and now conveniently using it to artificially instill a inflation control (not original intent) is a little suspect.

We could do some simple algebra and figure out what the price would need to increase based on your above figures to hold a basic rate of return of say (200 a month) per rig. Bottom line the the last month would have to have ethereum at 3k per coin if you were only earning 0.067 a month to = 200USD.

Ethereum having a halving event, continue with hashrate predicated mining difficulty until they are ready to engage PoS seems like best play for the genuine market dynamics.