I think more people would want to continue using Blitz3D than migrate their project to BlitzMax or another engine such as VividGL.
If you upgrade the rendering engine in Blitz, it's just a matter of replacing the runtime library. The rest of your code will still work because CreatePivot() would do the same thing and RenderWorld() would do the same thing.
If you upgrade the rendering engine in Blitz, it's just a matter of replacing the runtime library. The rest of your code will still work because CreatePivot() would do the same thing and RenderWorld() would do the same thing.