To add to this, PC memory doubles in general about every four years in standard enthusiast level issue requirements, especially for games. For example, in 2010 4GB was the norm for system memory. In 2014 it was 8GB. Now in 2018 it is 16GB. In fact, many AAA title games these days recommend 16GB system memory with 8GB being minimum requirements (when using high quality settings).
Regarding video card memory, it will be a few years before that 8GB VRAM becomes a problem. Only recently have we seen 4GB cards start to show their age in games when it comes to maxing out quality settings at high resolution (2K and 4K specifically). If you plan on only staying at 1080p, you will be a very long time before that video card memory starts...