We are working very hard to push out a working WebGL 2 prototype
before the end of year.
There's no doubt that you do. I'm just pointing out the realities of adoption. I started measuring WebGL activation rate early 2012:
2011: (at a rough guestimate) ~30%
But that's the whole picture, different platforms differ, to wit, smartphones:
2015: (the big apple jump) 75%
But even inside a platform you get some interesting things to see, let's say android, overall the curve looks quite similar to mobiles in general (sans the apple jump), but then you get to ask, why? Well, android comes with two browsers, Chrome and Android "native" (some android vendor packaged version of chrome). To a large degree, "WebGL adoption" on android really means "Chrome adoption". To a degree this is generally true, adoption rate has some relationship to UA update rate. And UA update rates differ, wildly.
Chrome Desktop: ~1 months
Firefox Desktop: ~3 months
IE: ~3 years
Android: "it's complicated"
iOS: At most once a year (perhaps every 2) with a new iOS release, and then about 30%/year
But why do we even consider mobiles as a significant factor? Well, they make around 15% of the browser landscape. Generally it seems mobiles are more timid to adopt new browser features. Although the big "desktops are dead" movement hasn't happened, mobiles are still grabbing more market share, so this put s a bit of a dent into overall UA update/WebGL adoption long as they're lagging.
Of course there's also hardware to consider. A lot of mobiles do have ES 3.0 support, but also a lot of them don't. So how fast does hardware update? I can derive a rough guesstimate from that from the max texture size. Let's consider 8k textures as a watermark on desktops:
So how does that look on mobiles? We have to consider 4k textures there as the watermark:
From this you can derive a rough guesstimate how fast actual hardware in the wild turns over. And my guess here is that about 10% of desktop GPUs get replaced every year, and about 5% of mobiles.
So what is ES 3.0 support on mobiles today? Well Unity thinks it's about 4%.
The bottom line is, new WebGL 2 adoption will be long and grueling and hard to watch. It will happen, but slowly.