I'm not surprised to see PC building going away. It's a high risk, low reward enterprise, especially considering that modern games haven't push the minimum spec envelope much further than what you can play on a Macbook Air. Building a PC is like Lego, where the pieces only fit together in one specific way, and each piece costs $250. The good part doesn't start until the building is done and you get into the software.
But there will always be a place for actual hardware tinkerers, the ones who need multimeters and solder and flux. Even if it is a niche.
ps: in the wintel world, I wouldn't call software a good part, unless you enjoy removing windows and drivers crapware, but you probably had clean distributable ghost images of some kind.