The worldgen system already tries to abstract away things like continental drift by using a fractal heightmap generator. This generator will spit out things that look like lift plates and trenches. There is no way that continental drift would ever become signifigant, real life or DF, in any way for a civilization. Even 10,000 years would not be enough to notice it's effects, other than a few meters in-game, which is far below even one embark square in size.
Earthquakes could be nice, but before that was even an interesting phenomena in-game we would need some kind of structural integrity checker. As it stands now, you can balance an entire fortress on a block of soap, or hanging floor tile. IT doesn't even need to be "balanced", and can be on the very edge of that fort. An Earthquake should, ideally, bring this crumbling down but, then again, "IDEALLY" it should not be possible in the first place. So it's a cool idea... maybe for another game.
Meteorites can already be modelled by setting up a small soil or sedimentary inclusion mineral, and calling it "Meteoric Iron" or "Meteorite". A few mods spring to mind. As far as them falling to the ground and causing devistation, I bring up the time-scales (few signifigant meteor strikes have occured in the past 200 years on Earth. Tunguska and.... can you name another? I didn't think so. Tunguska didn't even hit the ground). So while a planet-wrecking collision is certainly possible, the chances of it happening during the time of a civilization is pretty slim. Even beyond that, any realistic modelling of a signifigant meteor strike in Worldgen would have it be the DEATH of Civilization, and after a very short time bring about the Age of Emptiness or some similar age in which all civilizations are dead. Civs can't survive if the sun is blacked out and crops do not grow.
But Natural Gas pockets? Melting Liquids? Volcanic Eruptions in both Worldgen and Fortress mode? I wholeheartedly support these. Especially the Volcanoes in Worldgen. Insta-ruins of any Dwarf Fortresses on that same tile. The Biome would change to Basalt Rock Desert, immediately. Realistic and !!FUN!!