I think that the new consoles are going to hold back games needing super high amounts of Vram, because everything is made to be played on all systems PS4/XBO they are still making games with the PS3/360 in mind. You don’t see many PC exclusive titles anymore. BF4 is one of the more demanding titles out right now and it uses about 2gb of Vram. Watch Dogs uses a lot of Vram, but it is currently very poorly optimized, I am sure that is going to drop with time/updates. People like to use Skyrim moded out as an example of needing high Vram, my laptop has a 2gb 770M, I run skyrim maxed out with 46 mods no problem.
I am sure nvidia/amd would not be releasing their new high end GPU’s with 3/4gb of Vram if it was not going to be enough for future titles, and I think that is just for the higher resolutions.
If you plan on jumping up to a higher resolution 1440+ then yeah you are going to want more Vram, due to the higher pixel count. But IMHO 2-4gb of Vram will be plenty for games at 1080p for the next couple of years. If you disagree that’s cool this is just my opinion.