Refractory-based complex concentrated superalloys (CCSs) have received significant research attention in recent years because they show great promise as next-generation high temperature materials, supplanting conventional Ni-based superalloys which have reached their fundamental limits due to precipitate solvus and alloy melting temperatures. Such alloys are typically BCC, and may be strengthened by ordered B2 precipitates, leading to a two-phase microstructure that looks remarkably similar to their Ni-based cousins. However, the thermodynamic higher-order nature of the BCC-B2 transformation, compared to first-order for FCC-L12, leading to fundamental differences between the two systems. This presentation will explore how these differences affect microstructural development, such as the observed “inverted” B2-BCC structure. Design strategies to overcome such barriers to practical application are discussed from a thermodynamic perspective. Critical gaps in fundamental scientific understanding hindering future development CCSs are also discussed.