I can't think of any serious competitor to Adobe After Effects. There are many apps that partially overlap e.g. Fusion, or 3D apps like Cinema 4D. Apple's Motio

I can't think of any serious competitor to Adobe After Effects. There are many apps that partially overlap e.g. Fusion, or 3D apps like Cinema 4D. Apple's Motion 5 (the latest version) was released in 2011 and is not considered a serious competitor. Another example is InDesign. There are other DTP apps available, but for professional publication design, InDesign is the leading DTP program. What Adobe has is "mindshare" amongst designers (and a wealth of tutorials, brushes, scripts, plugins, presets etc). But there are encouraging signs that some users are considering alternatives. Sketch (Mac only) is a suitable alternative to Illustrator for many (if not all) tasks. So is Affinity Designer (Mac only too, but a Windows version is in the works). Affinity Photo (Mac only again) is an alternative to Photoshop. Plus, there are actually a wide number of digital painting apps for both Windows and Mac (e.g. Painter, Clip Studio, ArtRage, SketchBook Pro etc). Like other posters have said, there is plenty of scope for new desktop apps to rival old established apps. So much existing software has poor UX. If you can develop a better UI and a better or easier method of accomplishing tasks, people will take an interest. Both Sketch and Affinity Designer/Photo have enjoyed a swell of enthusiastic users who champion those programs. Much of their success is precisely because they offer a different/quicker/easier/more comfortable way of performing tasks than the clunky, cumbersome UIs of their Adobe rivals. I'd hate to think that someone would give up on a desktop app because they think the desktop space is too established or settled. You might not topple your rivals, but you can certainly carve out a profitable niche.