Multi-threading: Is it really necessary ?

Conventional programming models consider multi-threading along with all of its concurrency problems as necessary evils that need to be mitigated. At least in theory, this is not the case.
To continue to quote Prof. Edward Lee “If we expect concurrent programming to be mainstream, and if we demand reliability and predictability from programs, then we must discard threads as a programming model. Concurrent programming models can be constructed that are much more predictable and understandable than threads. They are based on a very simple principle: deterministic ends should be accomplished with deterministic means. Nondeterminism should be judiciously and carefully introduced where needed, and should be explicit in programs. This principle seems obvious, yet it is not accomplished by threads.”
As will be seen while looking at AMPS implementation model that it is a completely thread less design for deterministic parts of the program and threads are judicially introduced where required and controlled carefully.