PCIe vs. Ethernet: is it really a this-or-that choice?

Recently, a question came to us from an inquisitive designer regarding what used to be called the "Fabric Wars", which lead to an intriguing discussion about the evolution of connectivity choices in embedded computing systems. The conversation that resulted in this blog post centers more specifically around those choices in OpenVPX and SOSA™ (Sensor Open Systems Architecture) architectures.