I’d recommend an AMD card for Linux use too, with the possible exception of doing AI stuff, but plenty of people do use Nvidia cards on Linux. I’ve used them before. It’s not unusable, if you want to continue to use your existing card.
And you can always just make your next upgrade down the line an AMD GPU. I mean, GPUs do age out if you’re going to be playing games.
One other reason to keep the GPU is that if you’re fine with your existing monitor, you don’t have to deal with finding a GPU with DVI output.
Maybe at some point down the line, when your current GPU doesn’t perform adequately, get a new DisplayPort monitor and GPU together.