[jimmrf]

Good point:

Power - per kW cost would not have fallen materially, but efficiency per instance would have improved

Land - flat fixed cost would not have fallen, but sunk cost on existing facilities no marginal cost only relevant to geographic expansion. Also, AWS would own so would be working from increasingly small amortized base

Maintenance - might improve marginally with scale and experience as improve leverage on physical infrastructure

Staffing - would expect headcount per instance to fall in the period and automation to simplify some roles, offset by rising wage

R&D - You are 100% correct this would most definitely be increasing in the period and illuminates an interesting nuance. I am probably perverse in thinking of the underlying 'core' service (compute, storage, etc) margins as funding R&D to compete by creating the suite of services on top