The custom computer building industry, encompassing those who build their own rigs from scratch and those who commission professionals to do it for them, is undergoing a renaissance. As we traverse the undulating landscapes of silicon and solder, we must consider the complex interplay of forces shaping the industry. We shall explore the potential future of custom computer builders by examining predictions and emerging trends, focusing on the implications for enthusiasts and professionals alike.

The technological leap in computer processing power, as enshrined in Moore's Law, has defined the pace of development in the computer industry for decades. However, we're now experiencing a paradigm shift, moving away from an intense focus on processing power towards a more complex matrix of considerations. This shift is driven by the rise in importance of parallel processing, energy efficiency, and data throughput, as well as the advent of quantum computing.

Parallel processing, the use of multiple processing units working simultaneously to handle tasks, is emerging as a critical consideration. While consumer desktop processors have typically featured 2-8 cores, the rise of data-intensive tasks like machine learning and virtual reality requires more processing units, leading to the emergence of many-core and even "mega-core" processors. However, the benefits of parallelism are subject to Amdahl's law— a principle from computer science that essentially says the potential speedup of a program using parallel processing is limited by the time needed for the sequential portion of the program. The implication is that more cores do not always translate into better performance, especially for tasks that are not highly parallelizable.

Energy efficiency, too, is becoming a critical factor. As chipsets become smaller and more powerful, the risk of overheating increases. The second law of thermodynamics ensures that any energy not converted into work will be wasted as heat. This means that the more powerful a computer becomes, the more it needs effective cooling systems to counteract the excess heat. However, designing such systems is a daunting task that requires a keen understanding of thermodynamics and fluid dynamics.

With a growing emphasis on data and its role in our digital societies, data throughput (the amount of data to be moved around within the system in a given period) is a crucial factor. This is why solid-state drives (SSDs), designed for faster data retrieval and transfer, have become a must-have component in custom builds. However, the trade-off here is the higher cost of SSDs compared to traditional hard disk drives (HDDs).

Quantum computing is another emerging trend with the potential to revolutionize the custom computer builder industry. Unlike classical computers, which use bits (0s and 1s) for computation, quantum computers use quantum bits or qubits, which can exist in multiple states at once thanks to the principle of superposition. This allows quantum computers to carry out many calculations simultaneously, potentially outpacing classical computers for certain tasks. But these devices are currently in the experimental stage and are subject to quantum decoherence, where qubits lose their quantum properties over time—a problem yet to be fully solved.

As we navigate the future, there's a clear need to balance the benefits and trade-offs of these emerging trends. There's also an increasing demand for broader skills in computer builders. They don't just need to understand the hardware; they also need to understand the software and the physical laws that underpin computing. Custom computer builders are thus poised to become the polymaths of the digital age, blending knowledge from computer science, physics, and engineering.

Moreover, to stay relevant, custom computer builders should focus on niche markets. The rise of cloud computing and AI suggests a growing demand for high-performance custom computers. Gamers, graphic designers, and data scientists will likely form the core clientele for custom builds, given their need for power, speed, and specific hardware configurations.

In conclusion, the future of custom computer building seems dynamic and exciting, but not without challenges. Those who wish to remain at the forefront of this industry must continually evolve, adapting to new technologies and trends while expanding their knowledge base. It is a journey that promises to be as thrilling as it is demanding, enriching the tapestry of technological evolution.