Declared distances are all well and good, but if I have 'committed' to the airport in question (ie, decided that I shall land there and burnt fuel accordingly, iaw current legislation), and then someone has crashed on the runway, I shall say 'Mayday' and land on the remaining runway length or a parallel taxiway or the apron or wherever I choose. That's what the rules now provide for. Of course, you won't issue me a clearance to land, but I have taken my decision! having informed you of my decision, you will provide me with a service, albeit probably just an FIS and AS at this stage, but you'll certainly give me the surface wind and other information.
In this question, the questioner has posed a multiple-failure situation, which the rules do not currently address. But, the 'powers that be' have decided that this is all fine and dandy.
What they haven't done is to address the problem of aircraft which are short of fuel but not 'diverting', and the lack of clues to ATCOs that the aircraft on final might be short of gas. That's regulation!