These are strong points and I think the methodology behind Carbon is the correct one. The elephant in the room is that once Google decide to drop Carbon my existing code base will be dependant on a dead technology and then I am screwed.

I find it hard to trust Google to maintain any software nor to write software that is maintainable by a community. They write software for themselves and themselves alone.

Then wait for Google to adopt it at large?

If it (purportedly?) exists so that Google can move multi-million line code bases from C++ to something better bit-by-bit, because it's otherwise infeasible to do so, why would Google drop it after they have ported the first million?

You can simply wait to see if Chrome adopts it.

For me Go is a success story.