Since SAS is a relatively simple language, why can't someone just write a transcompiler that supports a subset of SAS and move it to R? That way you have the best of both worlds (sort of).
The most difficult thing about that is how you would treat "by" statements (SAS) vs the split-apply-combine (R).
Self-plug: I sort of made a quick hack about a month ago for SAS-Python, I'm sure someone with more programming experience than me
could produce something much better (I come from a maths background).
SAS isn't a language. It's a suite of (semi-integrated) products featuring numerous languages. Key among these are the SAS DATA step (analogous to awk), the SAS Macro language (which shares terms but is in fact distinct), a number of other global languages, a number of domain-specific languages (TABULATE, LOGISTIC, GRAPH, etc.), and some proprietary implementations of general standards (SAS SQL).
The best model for mapping from SAS to R is not to try to support all of SAS's functionality within R, but to use multiple tools. When UNIX was first created, with the awk and S languages ('R' is iterated 'S', Splus is the proprietary extension of S), awk was seen as the data pre-processor for S. Today you'd likely use R (statistical analyses, graphics, matrix language), awk, Perl, Python, Ruby, or C (general programming / data manipulation), a database tool such as sqlite or Postgresql (both of which have their own considerable analysis capabilities), and other tools as appropriate.
Trying to do everything in a single tool is a domain/application mismatch.
BAE Systems has a product called NetReveal that includes a compiler called "DataServer" which compiles a large subset of SAS into Java. Legend has it that the original author wrote the first version of DataServer in 6 hours on a train ride to visit his mother.
As a programmer, I was constantly frustrated by it. I felt that SAS as a language was pretty restrictive, especially when your algorithm wasn't a natural fit for the dataset model that it uses. It was like trying to shove a square peg into a round hole. It wasn't uncommon for me to sneak some Java straight into the output, but that wasn't really a sustainable / maintainable way to use it.
So your suggestion is doable, but I'm not convinced it's worthwhile.
The most difficult thing about that is how you would treat "by" statements (SAS) vs the split-apply-combine (R).
Self-plug: I sort of made a quick hack about a month ago for SAS-Python, I'm sure someone with more programming experience than me could produce something much better (I come from a maths background).
http://nbviewer.ipython.org/gist/chappers/8747253/stan_examp... https://github.com/chappers/Stan