A report by Sydney Morning Herald states that there are 634 runaways across 26 countries in the range of the plane's last location. Now, if it was an emergency, the plane could have landed in any of these locations.
Likewise, if it is a hijack, the plane could have been hidden in any of locations, closer to these runways. Hypothetical yes, but this could well be a lead for investigators to widen their search.
Let's make things easier yet again. A Boeing 777 would require nothing less than a 5000 feet runway. Rich Solan, an experienced Boeing 777 pilot added on to the speculations, saying that the plane could have been landed on a highway too, had there been an emergency.