Nicolas Cannasse has released haXe 2.01 that now has flash 10 support with a simple switch including the new Vector class.
Another very good news is that haXe has now complete support for Flash 10.
You only have to use
-swf-version 10as commandline parameter to be able to access the new Flash10 APIs (don’t forget to install first the FP10 from labs.adobe.com).
I think it is very possible for haXe to catch on big time, but it takes time as stated. Just remember that Python was worked on almost solely by Guido van Rossum for about 5-years, and then 10-years later it was picked up by Google heavily and the rest is history. I think it takes 10 years for anything to really catch on from standards to languages.