NI will not be implementing this idea. In the current LabVIEW, run mode has a well-defined behavior that goes beyond making the panel view as if it were running. It also reserves the VI for invocation. Although the change requested here is minor, it is not a priority for the current LabVIEW platform to change such a long-standing definition... it would require introduction of a new locked state distinct from "run mode" so that programs that query VIs about run mode do not erroneously thing the VI has no errors. That kind of breaking change in functionality is something we are trying to avoid in LabVIEW these days.
In LabVIEW NXG, the handling of the front panel is entirely different; as of this writing, "run mode" is not even a concept.
Anyway, I imagine it is easy to create a plugin which puts (and removes) the whole BD inside a disabled structure for testing the FP looking...So in this way we get the required functionality.
National Instruments will not be implementing this idea. See the idea discussion thread for more information.