OP, since your primary goals are gaming and content creation, you should aim for:
- Several CPU cores to handle the editing part. Ryzen systems are pretty good about this.
- An NVIDIA video card at least 4060 or better, their NVENC encoder is usually best for professional use. AMD Radeon is more cost effective. Since you're in the 2k price range I'd recommend a 4070 Ti or a 4080.
- I'd personally recommend at least 2TB of OS/game storage on an SSD and a 4TB hard drive to store personal files, just to get started. The reason I say pick a hard drive for your other files is because they're at least 40% cheaper and you'll have a lot of room for clips and previous recordings without burning your entire 2k $ budget.
- 32GB of RAM.
Unless you plan on playing retro games or you have a physical media collection somewhere then the need for an optical drive bay is almost none. Almost any cheap ATX mid tower case is good enough for you. A bigger one is good if you hoard a lot of gameplay clips like I do and need room for more drives in the future but it's not a necessity. That being said, you were concerned about "future proofing", I feel like something like the Phanteks Enthoo Pro probably has you covered if you want a case that you shouldn't ever need to replace as that has plenty of expansion for basically every type of system. Otherwise, just go for a cheap mid tower on PCPartPicker around the 50 to 70 dollar price range and save your money for a better video card.