Epcot hasn't really ever been without a nighttime fireworks/laser show. During its first three years, the show changed each year until Laserphonic stuck around for 4 or 5 years. Then GE began sponsorship in 1988, I believe, and Illuminations debuted. That show lasted until the WDW 25th anniversary in 1996, and Illuminations 25 began. Then as the Millennium approached, the show was completely made over as Reflections of Earth. In my opinion, each show has been better than it predecesor - although Illuminations 25 was extremely good. My sentimental favorite, though was the original Illuminations. My first trips as a paying adult were during the earliest years of that show. I have fond memories of leaving the park with Spaceship Earth "revolving" via projected laser continents.
Having Illuminations in the park definitely adds a signature, and from the business side - helps fill the many World Showcase restaurants each night. So, I would be truly surprised if we went without a nighttime fireworks/laser show at Epcot. We've enjoyed this one for nearly 7 years now. It's lasted just about as long as any of them, so I won't be too crushed if a new version was launched, especially if it lives up to the level of quality already established.