That's not a fundamental restriction or design problem with Julia, you're just describing JIT compilation. Plenty of languages can be compiled either ahead-of-time or just-in-time. Actually, this should be unusually easy for Julia, because their JIT compiler isn't a heuristic-based compiler like JITs for Python or JS.

The problem is funding. There are 0 full-time employees working on this issue because JuliaComputing has gotten about 10% of the funding Mojo has.