It's a lot to consider.
Really, the only thing that separates "us" from "them" as you put it is that we typically use vector art. C++, DirectX, C#, ActionScript 3.0, and whatever other OOP you can think of are just minor variations of each other and they don't change too much from year to year.
What really separates the main stream gaming community from the flash fanatics are their respective target audiences. For the most part, flash games target casual gamers who have maybe 10-15 minutes of time on their hands and just happen to have access to the internet. These people are on their lunch breaks, waiting for class to start, or (in some unfortunate cases) trying to get through a boring lecture. Main stream console and PC games focus on people with a bigger budget, a comfortable setting, and anywhere between 30 min - 8 hrs (we've all been there) of time.
But going to back to original question of, "Are we going to be retro?" Sure, but not in the way you think. It's easy to tell a retro console game based on it's graphics and what you play it on. And a PC game with display it's age through graphics, features, and compatibility issues with newer OS's. But flash games will always look and feel new. The internet is not going anywhere, so the older games will never be "phased out." Plus, because vector art is mathematically derived through the use of a few points and not dependent on how many pixels, polygons, or bump maps you can cram on a screen, flash games will always look as crisp and clean as their newer counterparts.
So really, yes, flash games from 5 years ago are retro, and yes, the games we make today will be retro five years from now. But will anyone be able to tell the difference? Will, the bored student, or casual gaming cubical drone be able to label them as retro? No, I don't believe they will.