Here's my perspective
The degree PC users can benefit from multi-threading (and their interest to purchase new hardware and/or software) depends on two factors:
1. The type of PC hardware support for multi-threading. This can be in the form of MP system (expensive and small volume), Hyper-Threading Technology (Mainstream pricing, mass volume with moderate MT performance benefits), dual-core processors, and quad-core processors in the future.
2. The availability of commercial software infrastructure that can effectively use processor hardware with multi-threading capabilities.
Back in 2003, the market place is such that (a) there are few MT applications for mass market; (b) Intel has sufficient manufacturing volume but can only devote limited die space in a processor package on hardware multi-threading. Hyper-Threading Technology is an efficient (die-space-wise) way to enable mainstream processor hardware with multi-threading capability, given a small amount of die-space per processor package. Even though HT only provides moderate performance benefit to multi-threaded applications, it improves UI and I/O responses. As a result, even though there are few MT applications, consumers can benefit with multi-tasking usages in the absence of wide varieties of commercial MT applications.
Moving the clock two or three years forward with silicon process improvement and feature size reductions, Intel can devote ~50% of die space on hardware multi-threading in a processor. However, this pace that Intel can introduce dual-core processors out-paces the speed that commercial software ecosystem can migrate from single-threaded paradigm to multi-threaded design. So the priority of enhancing hardware multi-threading feature at this time is on providing more MT performance benefit per processor package, versus the number of threads (logical processors) a processor package can support.
With respect to the availability of Hyper-Threading Technology in future processors, you should not rely on conjectures or innuendos purported by some web articles.
Although I am not at liberty to discuss future product roadmaps, I'll leave you with these thoughts:
In the IA-32 Intel Architecture Software Developer's Manual, we strive to provide guidelines to help multi-threaded developers to write code that works well with any form (or combination) of HT and multi-core capability. The latest version provides guidelines for MT software to use shared L2 on an Intel Core Duo processor efficiently, and it will continue to support MT software with guidelines to use HT features effectively because Intel values greatly the engineering investments that software developers had made in the past on HT.
As commercial software ecosystem for multi-threading proliferates in the future, I believe the priority in future processor feature enhancement relative to adding number of cores per package vs. supp orting more threads (logical processors) per package through efficient die-space, can grow (or alternate) in either direction. Either way, it will enable growth of multi-threaded software eco-system and end-user interests.
You can find the most recent edition of IA-32 Optimization Reference Manual at
Together with the IA-32 Software Developers Manuals, they provide a unified solution for multi-threaded software to detect and recognize different processor topology and/or cache topology across any combinations of hardware multi-threading capability.