"The Death of the PCIe Expansion Card" seems like an extreme description of the latest set of motherboards having "fewer than five" PCIe slots.

Yeah, the numbers have shrunk over time, but I think that's probably due to USB and perhaps to some extent HDMI making an expansion card unnecessary. Also, motherboards have enough hard drive controllers in them now that most people who would add a hard drive to their PC have no reason to need an expansion card to do so.

I don't particularly like the trend either, but I think PCIe is far from dead at this point.