Just to give my insight on placement... They could do a mini-land (or a smaller land for Star Wars) between Discoveryland & Fantasyland outside the train tracks. If it's at Walt Disney Studios, (which desperately needs additions) it would work perfectly in its current design. In fact it needs to happens! But Marvel might be a better choice first. I strongly disagree with Star Wars invading Space Mountain permanently at DLP -- it's style does not suit Star Wars at all like at Disneyland in California. The back of Discoveryland is almost like a mini-land as it is more retro futuristic (80'sesque).
I definitely think The War of the Worlds would work although to be completely honest, I only know of it by name and not really anything else. Would the launch (catapult cannon) make sense story wise? Like could it be renamed without altering the structure?
Going back to the talk of Walt Disney Studios... It's not only in dire need of something new (especially an aesthetically pleasing land), but the entire park, on a scale far larger than California Adventure & HWS, needs to completely be redone. This includes all the sidewalks, facades, and landscaping.
I'd say if Fantasmic! would ever go in the park it would have to go on the left side of WDS (in an arena like HWS) as to have minimal impact upon Disneyland Parc Paris, and I'm certain that they would love to put in a true night show in that park if they were to spend billions, so there's that to consider.
While there is nothing in the novel about human spacecraft or rockets fighting back, I suppose you could add it in anachronistically. I'm attaching a picture that I think is in the public domain. One has a depiction of the alien machines fighting a British naval vessel. Disney could probably create the alien machines for Space Mountain with a similar design. The other picture, which I was unable to attach, is licensed, but it is from an advertisement for the 1950's Paramount film, The War of the Worlds. You can find pictures from Wikipedia depicting the alien craft. The problem for Disney would be securing the rights to that design from Paramount. In the past, Paramount has placed attractions in Universal Studios parks when they couldn't place them in their own parks. It is really iffy whether Disney could secure the rights, but I believe the 1950's movie has the most widely seen depiction of the alien ships in The War of the Worlds. I'll attach the picture now:
