Conclusion
Whenever I read sentences like “What a ripoff – Intel doesn’t even solder a 300 USD CPU” or “Why does intel save 2 USD on soldering” I’m thinking
Stop hating on Intel. Intel has some of the best engineers in the world when it comes to metallurgy. They know exactly what they are doing and the reason for conventional thermal paste in recent desktop CPUs is not as simple as it seems.
Micro cracks in solder preforms can damage the CPU permanently after a certain amount of thermal cycles and time. Conventional thermal paste doesn’t perform as good as the solder preform but it should have a longer durability – especially for small size DIE CPUs.
Thinking about the ecology it makes sense to use conventional thermal paste. Gold and indium are rare and expensive materials. Mining of these materials is complex and in addition it’s polluting.
After soldering one of my 6700K CPUs I can tell it’s a pretty complex process. I’m still working on it and trying to make it available for extreme overclockers. However, I doubt that Intel will come back with soldered “small DIE CPUs”. Skylake works great even with normal thermal paste so I see no reason why Intel should/would change anything here.