> If we had that information, then you could answer some of the questions asked surrounding the deprecation schedules of HW in a DC the size of Amazon.

But we still don't, so we still can't infer anything at all from the announcement schedule.

Moreover, assuming AWS is growing fast enough, new instance type announcements could be entirely decoupled from deprecations. Even with both sets of data, it may not tell us anything about overall replacement rate, without also knowing the overall growth rate.