yea, been there, done that:
Yet, it doesnt seem to be a problem currently.
People does not actually seems to restrain themselves from transacting more on a daily basis like your table would like to suggest.. but they just dont, right?
Personally I transact mostly offchain (trading plateforms).
Maybe buy couple products or services per month, but i mean, like it or not, bitcoin is not as handy as cash or credit cards for everyday purchases and even more for the average joe you keep on appealing.
Imho, we could easily go beyond 10 million bitcoin users without any difficulties regarding scaling.
As to when this would happen, Im not going to guestimate there..
But luckily this would give us enough time to investigate further on.
Was it not stated that when this becomes a problem, there probably won't be enough time to act? Indeed, there is no problem in the present, but there will be one very soon.
Explaining the main chain is difficult enough, trying to get people to understand offchains too is a bit much.