I'll address the binary compatibility concern. I think at this point for the average scala developer, binary compatibility isn't really a big deal anymore. At this point the releases require very few (if any) changes to the codebases and all the library maintainers have stepped up their game with releases corresponding with new versions.
Sure, it'd be great to have binary compatibility, but I think the ability to make changes to the language unhindered by supporting byte code from previous languages is more valuable.
For example with the 2.11 release, I had three different non-trivial sized projects and for each I was able to simply change the scala version in my sbt file and everything worked just as it had before with no library or compile issues.
I will agree that it was a huge issue in the past with 2.7 - 2.9, but in my world it hasn't bitten me in a long time. Definitely not trying to say it isn't an issue or something that wouldn't be great to be fixed, but at this point I have a tough time seeing it being considered a barrier to entry in any way.
Also, I just throw in that for me compile time hasn't been an issue for me lately either. I work on reasonably sized projects, but definitely nothing on the twitter / foursquare scale.
"This is why goroutines, everything on the JVM, etc are not going to work."
I've used Akka very successfully on the JVM for non-trivial clustered applications where performance is important, and I'm pretty sure the existence of most of google's infrastructure says that goroutines work at least a little bit.
Do you mean not work well? They won't gain traction?
If I remember correctly the CLR implementation of Scala was scrapped because there were some limitations with the CLR's reified generic type system that made it impossible to express scala's type system.
I even believe that Microsoft research tried to find a solution for a while, but were unable. I'll try and find some references if I can.
If google is providing you a free service, and giving you exactly what you want in that first result, why shouldn't they get money for doing it? Seems like a win-win to me.
Plus these look more like customized brand pages for companies that people are "specifically looking for", I would rather have detailed information about a company right front and center when I'm looking for it. The fact that anyone makes money because of this fact is ancillary.
SBT provides incremental compilation, so it's not really all that painful provided your using SBT to build your project. Additionally, your getting a hell of a lot of work out of that compiler.