I wonder if one day we will find that sending all data to a data center for processing doesn't scale. I think that's already a given for some realtime'ish types of applications and it could become more important.
Obviously, the success of decentralised computing depends a lot on the kinds of connected devices and whether or not data makes sense without combining it with data from other devices and users.
With small mobile devices you always have battery issues. With cars, factory equipment or buildings, not so much. But management issues could still make everyone prefer centralisation.
Of course it scales. Some problems demand more scale. Through more datacenters at it. Tweak the algorithms to distribute data more conservatively.
If sensors produce more data and data centers can process more data but network capacities can't keep up, then the analysis you are suggesting will show that we need more decentralised processing, not more data centers.
I don't think we were disagreeing; I was just pointing out that data centers scale very well for what data centers were built for. It's not that surprising that we are outgrowing them.