DESIGNING an MASL is one thing, SELLING it to a wide audience is another thing entirely. If you think you could sell it to current ASL'ers consider some of the problems:
1) A large percentage of current ASL'ers buy only MMP products EXCLUSIVELY (so you would have to convince MMP to find the time and resources in their already- full agenda to produce and market a MASL game),
2) A LARGE percentage of ASL'ers will only play HISTORICAL scenarios, EXCLUSIVELY (so you couldn't sell them stuff such as was found in MBT),
3) A large percentage of ASL'ers seldom, if ever, play Pacific theatre because they don't like to play infantry-only scenarios, with dense (non-urban) terrain and short ranges of engagement (so you would probably have a hard time convincing them to play Vietnam MASL),
4) Most ASL'ers demand a game which includes all the "bells and whistles" (technologies) typically used in the historical situations they are attempting to simulate (so anything representing modern combat would have to integrate, fairly seamlessly, rules which would surely be rather complex in order to include the planes and helicopters, and all the miriad types of artillery usage and other ranged weapons which have become available),
5) For many ASL'ers our playing time is quite limited (especially us older codgers) and we already have a game we like very much which takes so much of our available time.
With a lot of hard work someone might develope a good MASL, but for the above mentioned reasons, as well as a lot of other individual and personal reasons, I just don't think you could ever expect to interest any significant portion of current ASL'ers.