Some of you may still be asking: beyond copying design or sharing pieces of code, why won’t Mozilla switch to WebKit?
But to answer the question “why not switch” directly: the switching costs for us, in terms of pure code work (never mind loss of standards body and community leverage), are way too high for “switching to WebKit” on any feasible, keep-your-users, current-product timeline.
At the Mozilla mission level, monoculture remains a problem that we must fight. The web needs multiple implementations of its evolving standards to keep them interoperable.
If we at Mozilla ever were to lose the standards body leverage needed to uphold our mission, then I would wonder how many people would choose to work for or with us. If Servo also lacked research partners and good prospects due to changing technology trends, we would have more such retention troubles. In such a situation, I would be left questioning why I’m at Mozilla and whether Mozilla matters.
The truth is that Gecko has been good for us, when we invest in it appropriately. (There’s no free lunch with any engine, given the continuously evolving Web.) We could not have done Firefox OS or the modern Firefox for Android without Gecko. These projects continue to drive Gecko evolution.
And again, don’t forget Servo. The multicore/GPU future is not going to favor either WebKit or Gecko especially. The various companies investing in these engines, including us but of course Apple, Google, and others, will need to multi-thread as well as process-isolate their engines to scale better on “sea of processors” future hardware.
Indeed more is at stake than just switching costs, standards progress, and our mission or values.