it just depends on how you define computer.

people will own an increasing number of dumb terminals connected to rented services.

does that reduce the number of computers? well, no..

so, imo : the trick isn't to reduce physical ownership of devices, the trick is to make it so that you need Big Iron in order to do anything.

One way that might be achieved is by forming social and cultural dependence on models so large that no one individual could possibly run them...