We haven't ruled out VSS support outright, but it's not an immediate priority for v1.0. We will review this after the initial release, and it will have to be based solely on business grounds.
Visual Source Safe's market share has been steadily diminishing since Microsoft announced its "end-of-life" plans, with support ending in mid 2011. What are your plans beyond this? Microsoft are offering "TFS Basic", which I imagine will be better value than the full version, but I don't know if the pricing has been published.
http://blogs.msdn.com/bharry/archive/20 ... users.aspx
Out of interest, which applications do you rely upon that don't have Subversion support?
Red Gate Software