8 GB of RAM should suffice plenty for time to come. All games run in 32 bit mode, whcih can use max 4 GB of RAM. Some few games are 64 bits but also have the 32 bit mode in them otherwise wouldn't sell.
If gaming 8 GB RAM is sufficient, anything else than gaming like virtualize video editing or such u might get teh 16 GB.
While we still have OS like win7,win8 with a 32 bit version to it, gaming industry wont go forward with 64 bit development. Meaning no more than 4 GB ram will be used by any 32 bit game.