Considering this as JSFiddle or Codepen alternative, I would find difficulties in using it, having in mind all of these projects that Mozilla killed lately.
I hope that Mozilla will finally figure out exactly what are their goals. They won't gain trust by releasing something promising and dropping it while after because it didn't match their expectations.
There is no reason for using native extensions in scripting languages like Ruby when program load is pretty low (especially when they are used for performance reason, not binding).
Great insight, though. Author described this experience as it was a great venture... in hindsight I suppose :-)
Beginners should comprehend essentials of Objective-C first and then learn Swift. At first there will be demand for Objective-C since a lot of companies already use it. But over time it should change in favour of Swift (more aggressive promotion by Apple).
Swift is a replacement for Objective-C in Apple world. But that doesn't mean Objective-C is going anywhere. It has rich ecosystem and experienced developers all over the world.
You can create application using both languages simultaneously which allows you to use mature libraries or frameworks in Swift.
Language is a tool. Companies don't hire programmers for knowledge of specified language but for the ability to solve problems.
I hope that Mozilla will finally figure out exactly what are their goals. They won't gain trust by releasing something promising and dropping it while after because it didn't match their expectations.