Pull request for 3.5.0 is at https://bitbucket.org/larry/cpython350/pull-requests/3/issue-24847-fixes-tcltk-installer-layout/diff. When merged, this can change back to normal priority for the rest of the fix.

Long term (probably 3.5.1, possibly 3.5.0rc2 if I can get it done) I want to build tcl/tk differently so we don't have the dependency on this unstable part of the VC runtime, but deploying it now is the easiest way to keep tcl/tk working.

The biggest risk is that extension authors may plan to depend on it - currently distutils bdist_ext does not use it, but that is already causing compatibility issues with old code (a.k.a. code that needs updating for a newer compiler), so there'll be a bit of wait and see. 

Maybe we'll just have to accumulate all versions of vcruntime*.dll from now until forever (and backport them), but I hope we can avoid that.