Metaprogramming will struggle to go mainstream. It's the way you shrink a 50,000 line program down to 1,500 lines that nobody can understand but the author. I absolutely love doing it and I think I could hand the code off to somebody and have them make small changes in the DSL code but if they have to change something in the implementation to extend the DSL all bets are off.
After all these years we still don't have macro assemblers as good as what the IBM 360 had even though we now have architectures that have enough registers that it would be reasonable to pass a register name as an argument to a macro like you could do in IBM Macro Assembler.
After all these years we still don't have macro assemblers as good as what the IBM 360 had even though we now have architectures that have enough registers that it would be reasonable to pass a register name as an argument to a macro like you could do in IBM Macro Assembler.