Sid Meier himself warned about the difficulty of trying to design games tat are multiple games at once, as basically everything in the list other than Lemmings is). His whole "one good game is better than two great ones" argument, as it's difficult to get a good balance of fun for any given player. If someone likes, say, the strategy elements of North & South, but not the battles, or they feel like they want more of one game but they have to do the other, there's some tension there. So you have to make the games be just fun enough, and change just often enough. A really hard problem.

And this is why it's relatively unlikely to find worthy successors: Making the whole be as good as the sum of its parts is hard enough. Getting to be as good as Pirates, or the best Cinemaware games, where the whole was significantly better than all of the games in isolation, is aiming foolishly high. Which is why, say, the xcom remakes are such a wonder, because they manage to both change the original two minigames underneath, improving them substantially, all while still being balanced.