Joseph there are a number of cross platform plugin systems, QT being the one that comes instantly to mind. QT also has nice graphics, multimedia, network, web support, etc that could freely (as in beer) be taken advantages of if the runtime were to become open source. I am certain there are other possibilities equally attractive possibilities.
If the goal were to get AGS runtime ported to multiple platforms then open source would be the way to go about it, IMHO.
The compiler is irrelevant to the preservation of legacy resource files which seems to be your concern. As previous posters suggest a new compiler output could be created that would be open source. The legacy format could be supported by a closed source binary in the form of a DLL, static linked library, ect.
If the goal were to get AGS runtime ported to multiple platforms then open source would be the way to go about it, IMHO.
The compiler is irrelevant to the preservation of legacy resource files which seems to be your concern. As previous posters suggest a new compiler output could be created that would be open source. The legacy format could be supported by a closed source binary in the form of a DLL, static linked library, ect.