That is assuming that the stricken aircraft had an abort routine with a non-standard heavy landing in an emergency mode coupled with an appropriately pre-recorded "Mayday! Get out of my way" message, all local METARs, an automatic 7700 squawk with an optimal quick'n'dirty "glide to the nearest threshold, disregard the weather and performance if it's just slightly out
With modern computing power it would take less than 0.1 second to perform all of above. Obviously it will take some time to program all this logic and get it tested and certified, that's why new regulations and guide lines need to be published soonest possible.
ps. Some of the major automotive manufacturers expect to release fully autonomous cars to the market in 2020. You can say it is not the same speed. True. But then road environment is also much less structured and less predictable. Current prototypes driving cities and highways without major issues, it took around decade to get there.