REF VOR RW08 scenario: If you're enroute when you go NORDO, you might not be with your final sector or might not have received the approach clearance. So, the likelihood of an alternate MA being received is slim. Unless there is a published FDC NOTAM with an alternate MA procedure, for planning purposes, you'd need another IAP.
The OP wrote about an ILS with an inop VOR for the missed approach hold waypoint. In that case, if so equipped, an IFR GPS could be used for the MA segment.
REF GPS overlay: there's an NPRM "out there" and I can't find it right now, but any how, it addresses the use of (proposes allowing) an IFR GPS for a non-overlay IAP during the final segment.