Annex 14, CAP 168 and aerodrome safety design
Lots of speculation, it's a rumour site, after all!
However, one aspect is apparent already; the design of the various protected slope surfaces, runway Strip and Cleared and Graded Area (CGA), Runway End Safety Area (RESA) and other aerodrome criteria has in this case proven to be entirely adequate. These distances/dimensions have been arrived at over the years by expeience with other accidents and incidents (I personally recall the Continental B747 getting rather too close to the South Terminal roof at LGW). Have a look in CAP168 for a lovely diagram bringing all the surfaces together; it looks a bit like a sports stadium with the runway on the pitch.
Recently, ICAO recommended that RESA be increased from 90M to 240M, good call!
Although the CGA has a 'neck' 75M either side of the Centreline at the runway ends, the Strip is still 150M and the closest holding point must be 90M from the Centreline. These figures for a Code 4 Instrument runway, which is what 27L is, of course. In this case the a/c slewed as it changed from one surface to another but a vehicle or aircraft holding at NB1 would have been OK.
Another aspect of aerodrome design that no-one ever sees is protection for undercarriage running in the soft, encountering the edge of a runway or taxiway. An underground ramp is constructed at all transitions to allow wheels to ride up onto the hard, instead of the gear being wiped off by a vertical surface. Unfortunately the main gear in this case was already destroyed but it does appear that the noseleg, although compressed into the fuselage, might well have ridden up the ramp. This safety provision is known as 'Delethalisation'.
Now, Public Safety Zones, there's a whole new topic!!
TheOddOne