The shortage is not entirely because of miners. Nvidia manufacturers switched to using slower RAM in some of their cards. This was actually a very smart move (they should expand it to all their cards IMO). If you want the fast RAM, you have to buy the "mining" version of the cards. So in theory, it should have no impact on the gaming market.

For some of the popular mining cards (e.g. RX 470/80), well they simply haven't been available in many places for over a year now. Their successors aren't that great for mining either because of the increased power usage and RAM "lottery" (you don't really know what type of RAM you're getting when you buy a card). But most gamers don't generally care about RAM speed. This is also why the 5 series is generally cheaper than the 4 series (where you can find them).

However, the biggest problem is that there simply isn't enough RAM. The RAM shortage is being driven by smart phone and GPU production, and suspected price fixing. Samsung said they plan on increasing production (apparently they don't like it their competitors who make inferior RAM are making similar profits), but we will probably only see the effect mid-2018.

https://www.dramexchange.com/WeeklyResearch/Post/2/4815.html

http://www.pcgamer.com/samsung-to-increase-dram-output-as-ra...