Comment by frjalex

I'd imagine it'd be hard for MSVC and gcc to fade away --- gcc has some notable architectural differences from llvm (such as having multiple, layered IRs) and on some optimizations gcc is stronger. While for MSVC they target Microsoft's own ABI. Unlike other technologies that already feature a monocultural landscape I guess it's fair to say there's no one, single, best way to design a compiler that accounts for the wide-ranging differences of backend architectures and frontend languages (in addition, when you compare the costs of developing a brand new compiler with say, developing a new CPU architecture, you'll find the price associated with the former is much more affordable, and might be reasonable under different circumstances).