Upgrade or keep? Is it worth upgrading right now?

My current rig consists of a 3060, i5 8400 (yes, underpowered, im aware of that), asus b360m-a, 650w psu and 16gb of ddr4. While it still runs basically everything i want, it is starting to show its age in more and more games, mostly cpu intensive ones (beamng, cities skylines 2, etc.), and making me turn down the graphics down to medium or so. I recently started looking into the motherboard, cpu and eventually the gpu (not straight away though). Would it be worth it to go on to am4 (budget for the mobo and cpu is <400 euro), get something like a 7 5800x, a not so high end motherboard, and as time goes get like a 3080? With this i could reuse my current ram and get 32gb later on as well. Gaming on 3440x1440.