The idea that the world is flat and that all evidence to the contrary is a vast conspiracy perpetrated by the airline companies is also out there.
The idea that Mass Effect is the gaming equivalent of Star Wars in the impact it has on pop culture and the gaming industry isn't quite that absurd, but it's equally as factually incorrect.
comparing something scientifically proven to something that is artistically subjective is a false equivalency, and not a good argument.
I bet there were tons of people who said the same thing when Star Wars came out, it would be a flash in the pan fad before it dies off eventually. I don't know, I wasn't around when the original trilogy was in theaters though, but I do know it changed how sci-fi and special effects were used and seen, that's for sure.
We see stuff all the time now in that vein too, maybe the problem is there is too much going on at once, so many different things and fandoms and cultures out there that encompass geek culture on the whole, its harder to penetrate to the level of Star Wars in terms of street recognition. Plus age is a factor, forty plus years of growth and the mass-commercialism of Lucasarts allowed Star Wars to be continuously relevant for mass appeal, but the bigger point is how it continues to influence I feel.
I don't think it's an issue of numbers really, but relevancy like you said is the key outside of the gaming industry. Even you admit a lot of what BioWare did with Mass Effect has been seen elsewhere in video games, and it will continue to be seen. Hell, Fallout 4 is doing the convo wheel now, thats kind of significant, and just one example.
But the outside factor is still present in this. People recognize Mass Effect a lot more than other games out there now, there is merchandise, in-jokes, fandom, all that pop culture stuff sharing space with comic books and Dr. Who and Star Wars, and then you have the academic side of things; using Mass Effect as part of a thesis on game evolution, morality, religion, philosophy, scientific theory, literary theory, all good and bad of course too. That is how good works of art really shine; by how they are treated over time with serious and critical eyes.
Combine the two, the relevancy and the impact, you do have something id say.
I don't know. I guess it might be pretentious to say it, but it just feels right I guess to compare it to the biggest Sci-Fi universe in the world. I guess i'll take the zen master approach and say "well see" a decade from now at this point.