I blogged last time the browser engine count changed, so I think to be fair I should blog about this one too.
I think this is good news for the Web. When we lost an engine, that was bad for engine diversity and the open Web. Now we're gaining one, and that's good for engine diversity and the open Web. It's not a direct reverse of the Opera situation though. Compared to Presto, Blink will have much more market share, and therefore a bigger impact. On the other hand, Blink is a promise to deliver a different engine over time, not a new engine right now, and even in the long term one presumes it will share a lot of code with Webkit --- especially if people port code between the two projects. So it contributes less diversity than Presto did.
One immediate benefit for the open Web is that today it's difficult for mobile Web developers to advocate "just coding to Webkit" as the way forward.
One issue we'll need to figure out in standards groups is when a Webkit implementation and a Blink implementation of a feature count as two independent implementations to allow a spec to proceed to REC. It's tough; even if the implementations are developed independently, the shared context (both code and architecture) will make the implementations less independent than they should be. We may need to address this on a case-by-case basis.
I am a bit worried about how this will impact Apple's support for the open Web. Safari has lagged behind other browsers in various ways, but they were also dragged along by Google to some extent in supporting new features whether they cared or not. Now they're falling completely off that train and we'll see a true test of whether Apple is willing to step up their investment to keep up with the progress of the open Web. Apple has obvious incentives to hobble Web apps on iOS, so I worry.
Of lesser importance, this is probably good for Mozilla. Even if it means Chrome moves faster, the fracturing of the Webkit community benefits us. It's not something to gloat over though.
Back to work!
Update One other thought occurred to me: now, a company adopting Webkit has to choose between a fork dominated by Apple and a fork dominated by Google. That's going to be less appealing than when Apple and Google were providing some counterweight to each other.