Even if Linux does not become a successful competitor in the personal computing market, it will still have its niche in mission-critical and specialized computer systems. The availability of its complete source code is a rare feature not shared by any other operating system of its sophistication. This allows researchers and engineers to know everything about how and why the operating system works the way it does. In space shuttle experiments or even just elevators, the engineer needs to be able to predict how and why a computer can fail, which is obscured by not having the source code. Linux's source code availability also allows engineers to build one-of-a-kind computer systems with a modified version of the kernel. These systems include supercomputers made from clusters of Linux PC's tuned for their task of number crunching, such as the Beowulf cluster at NASA and the cluster made by Digital Domain for rendering scenes of ships sinking in Titanic.
However, most of Linux's momentum comes by virtue of its reliability, performance, and economics. When Linux is installed on a computer, it usually stays there, assuming the user has the experience and patience to deal with Unix. Information technologists can relate many stories of companies that running Linux servers that decide to try using Windows NT. Most convert back to Linux within a week due to reliability and performance issues. Linux also excels in economical factors, since for little or no money, most distributions can provide services equivalent to at least $5000 of commercial software. It would be difficult at best to undermine this type of competitive advantage.
Furthermore, since the source code to is freely available, the operating system has been ported to work on many more architectures. Initially intended for Intel PC's, Linux now works on every major hardware platform, from Macintosh's PowerPC and Motorola 68K platforms to Digital's Alphas to Sun's SPARCstation. Developers are also making versions of Linux for more esoteric hardware, such as the PalmPilot handheld computer. Torvalds has joked that the ultimate goal of the Linux project was ``complete world domination.'' Although the propagation of kernels may seem to point towards this goal, the variety assures that the project is not bound to any one particular architecture that may become obsolete or die out in the near future. For this reason, the momentum behind Linux will likely continue a fair distance into the future.