I haven't seen the roadmap for C99. It would be of great interest since portability in embedded software is important and many compilers support C99 whereas Microsoft does not.
It is good practice to build embedded software for PC target as well (for simulation awaiting hardware to be done or for ensuring portability). Visual studio is a productive environment with great number of experienced users so it is a shame that it is really bad at C99. This forces us to select other PC development tool chain.
/Peter