Unfortunately, SWAT 4 is a game that will probably be annihilated by the legal mess it is in. Nobody knows who owns which piece of the whole among licences, intellectual property and whatnot, and I doubt the parties involved will even think about renouncing to their potential rights "just" to preserve a classic.
You've got to love Capitalism! What kind of world will this be without some hungry bastards pushing their own creations to oblivion rather than share something? Better gaining nothing and let a great game die than allow anyone else to profit, right? :P
More seriously, that is a real modern plague that threatens art -of any kind- like nothing else, imo.
By the way, I have been very
lucky: just two months ago, I found brand new (well, more like "not yet used or opened", since thay have been produced years ago) physical copies of both the original game and the expansion for 2,99€ and 4,99€ respectively, the last in stock. What a deal!
Can GOG try to negotiate with the actual owners of the rights to release a GOG version?