I think chess will always have its steady fanbase. I mean, let's face it, it has never been, and will never be, as popular as major sports, e.g. soccer/football.
Real time strategy games IMO are something very different to games like chess. As you said, the most important skill in these is to be able to operate your mouse at 100 clicks per second, while knowing and using several dozens of keyboard shortcuts, and of course knowing the exact course of action to build your bases in least time (not compareable to millions of different chess openings). Another difference is that you normally don't see what your opponent is up to until he comes knocking at your doors. Also, luck is always part of the game.
Don't get me wrong, I do like that kind of games!
Then we have those round based strategy games. Speed isn't a factor anymore, so they're probably more similar to chess. Some of these are really complex, it may take you months to fully understand the rules and possibilities. Some are just 1:1 conversions of (sometimes also really complex) board games. You may even think of chess as the father of all these games.
For me, and I think many would agree, the beauty in chess lies in it's simplicity (the rules, I mean
), it's ancient history, and its determinism, it's lack of chance. I do like many strategy games: card games (e.g. Skat), board games, computer RTS games, ... But when it comes down to it, nothing beats a game of chess.
But you have to pose the question why people play computer games in the first place. Most importantly, you can play these any time, there's no need to wait for a friend to come over and play. You just push the button and play against the computer AI. Still, at least for nowadays games, there will eventually come a time when you know what the computer "thinks", know his strategies, and will hence learn to beat him. The next logical step is to play against other humans, play over the internet. This development created a whole lot of new opportunities: you can play (against humans) whenever you like, play opponents from all over the world, are always able to find someone who plays at your very level, not to mention getting to know people by playing against them...
But here, all those games co-exist side by side with chess (people are playing online chess for the very same reasons), and I can see no reason why chess should ever become less popular.
... with one exception: the day that computers are able to solve chess will probably be the beginning of the end. That day may still be far off, but we have to face that it might come eventually. The game of (Nine Man's) Morris (Merrills / Mill / Mühle) has already been solved in 1993 - the last world championship was held in 1997. Computers are working 'round the clock to solve Checkers (Draughts / Dame), several openings have already been analyzed to a draw. In 1994 a program took over the Checkers Man vs. Machine World Championship.
And we all remember when Deep Blue first beat Garry Kasparov in 1997.
Maybe we will learn one day that chess is always a draw with perfect play, and people will move on to more difficult games (maybe Go?). Computer games take an ever increasing role in creation of new games, so maybe one day, very far off in the future, a computer game will become the holy grail of strategy games.
But until then, let's play chess!