VRAM requirements are way overstated. 8GB is fine for most people. 55% of Steam users are still on 1080p with another ~8% or so on comparable resolutions like 1920x1200 or under 1080p; so almost 2/3rds of their user base. It's good to future-proof, but it will be many years until 8GB VRAM becomes a true bottleneck.

B570 does seem like a solid option for the value space. That being said the B570 is closer to $290 (full out of pocket price) where I live. B580 goes for about $340. I feel like if you are paying ~$300 for a GPU, might as well save up another $50 and get the B580.