I'll know we've reached AGI when they don't release an API for the model selling access for a few bucks per task. Seems like AGI would be worth more than that.
If I had true A(G|S)I, I would release patents, not an API.
We know they'll have replaced horses when a car costs 200 horses.
As long as there is more than one substitute, the prices are not set to equal value. (edit: assuming optimal pricing strat.)