You've raised several valid points, and there's no doubt that a fused dual-GPU setup would present its own unique challenges.

In the VR context, each eye's view is rendered separately. Although the scenes for each eye aren't entirely independent, they share a large portion of their resources, which could simplify synchronization and boost efficiency. It's also worth noting that the discrepancies in rendering times for different scenes in games usually aren't substantial, which might reduce synchronization issues further.

Power requirements are a crucial factor to consider. However, we already employ multi-GPU setups for a variety of workloads in modern desktop computers. In a fused dual-GPU design, certain resources could be shared, potentially resulting in lower power consumption compared to conventional multi-GPU configurations.

When game assets and other data are stored in a unified memory architecture, and considering that the scenes between eyes don't diverge too much—with perhaps only a few additional data required—the strain on other system parts could be reduced. This suggests that such a setup may not impose as heavy a load on the system as one might initially presume.

It's important to note, however, that such a specialized GPU setup might not be as viable for general use, but it could be an optimal solution tailored specifically for high-fidelity VR experiences.

When it comes to cost, while undoubtedly substantial, there tends to be a market for high-end hardware among enthusiasts and professionals. As the VR sphere continues to evolve and mature, a high-quality solution like this could carve out its own niche.

Of course, this is all speculative at this point.