Based on what I've read, you are correct, and plastic might never really decompose. It breaks into smaller and smaller pieces which are stable enough to stay plastic essentially forever. That 1000 to 2000 year thing that I read about contradicts some other things I've read, so it's pretty confusing. I need to track down that article and clarify this.

The best thing we can do as a species is eliminate as much plastic waste as possible.