I'd have to disagree. There is an essentially unlimited/infinite number of ways to arrange a script to make it unique/original. I'm no good at writing, but I can easily come up with a unique story. It might just be boring.I don't think there's any truly original ideas, no, but I do think it's possible to get something original and unique out of an established idea. I wouldn't say we've completely run out of those just yet.
For example:
A alien race of human-sized, highly intelligent gerbils visits Earth from another galaxy. At first the world is shocked. But the gerbils are friendly, say there are no alien threats, and offer to completely overhaul every nations' infrastructure to be suitable for efficient electric cars, which they also provide. They then say goodbye and leave. Everything returns to normal on Earth, and people soon stop talking about the alien gerbils.
But in reality, the gerbils never left. They hid themselves several hundred meters under Zimbabwe. After 50 years, they secretely establish a tunnel to Poland, where they secretly install puppet leaders of Poland and Lithuania. Their goal? To restore the medieval Polish-Lithuanian commonwealth. They give advanced arms and supplement these two nations' troops with special powers (unknown to the soldiers). They then procede to reestablish the Commonwealth by force.
Then they unmask themselves, announce that their plan succeeded, and leave Earth only to be destroyed in take-off by Mark Twain, who traveled to the 40th century and brought back with him the technology to destroy the gerbils.
Now I'm pretty sure that's unique. Of course, it's also stupid. But of course it's possible to create unique/original sci-fi stories.