More important than time schedule would the license of this .NET port. AFAIK, Visual Studio .NET's EULA forbids the creation of GPL'd software.
Notice that there's nothing from stopping people from making dotlrn components into "web services" (to use a current buzzword) through SOAP and other protocols that .NET uses. In fact, this is one thing that I'd like to do with some OpenACS applications. There are Tcl modules to do that already.