Depending on what you need Blender can be a replacement for After Effects. Blender can also replace Premiere so then you will have one workflow in the same program.

InspirationTuts has a nice comparison of Blender, After FX and Nuke which you might find interesting: https://www.youtube.com/watch?v=m3jArcnGr3E

As a replacement for InDesign I used Scribus a lot. It has some unpolished edges but gets the job done. It includes industry standard PDF exports.

I can recommend Affinity Designer as an Illustrator replacement.

I bought it when it was released and still waiting to be able to work properly with groups.

Inkscape is a decent replacement for Illustrator, at least in my experience.

Inkscape is great but not if you are working a lot in CMYK.

Yes indeed. But sadly not on macOS.

On what platform? Nuke is an amazing replacement for AE.

I really think they're very different applications. I think in nodes and much prefer Nuke, but AE being timeline based gives it very different strengths. Nuke also doesn't manage video and synced audio and is better optimized around frame sequences.

In school I'd often see people edit their projects in AE (because they were too lazy to learn Premere or another proper editor). It's not a great idea to use AE for editing, but its possible. If you tried to do that in Nuke you'd throw your computer out the window.

Sketch and Figma are amazing for UI work in vector.

Sketch is super bloated. Once you project grows perf starts to degrade quickly. Also working with groups is not great.