It would be cool if they would show the range of costs ($$$) for each step of growth. My fear is that if you do everything by the book the costs correlate with growth.
It would also be interesting to see that as a rough $$$/user. It would be very interesting to see how much you need to be making from each user to cover hosting.
I did this migration recently and we're spending about 1.75 cents per user. We could do it for cheaper, but we've recently had some issues that were absolutely trivial to resolve with AWS, that would have been very difficult with our previous hosting provider.
This hits on something in the calculation that I feel is very hard to factor in, the cost of development time. Sure, there are plenty of ways to do these things cheaper on a hardware/software cost per user basis, but more often than not I've found that we can get changes out so much faster in AWS that you're easily saving thousands in developer time, which would seem to more than cover the extra cost to me.
the rule of thumb is once you hit $20-99k/month, you can cut your AWS bill in half somewhere else. sites in this phase generally only use about 20% of the features of aws.
the other rule of thumb is once you hit six figures/month, you're probably spending someone else's money, are locked in to their stack, or just don't really care to begin with, so there's no point in telling/selling you otherwise.