Surely to goodness nobody would ever think of dreaming of doing that?
Hopefully they wouldnt, but how many people have been caught out on botched approaches? How many people fly made up approaches and run into problems? How many people have been caught out scud running? Clearly not something to plan to do, but might be a life saver when unplanned.
I think 'reliability' is more of a problem than the manufacturers would have us believe...
Not sure about that in the GA world, aleit you arent comparing like with like. In the GA world many of the steam guages are very old and the build quality may have not been up to much compared with the commercial stuff. On the other hand anything with glass will probably only be a few years old. That means across the GA fleet glass is likely to prove far more reliable. Compare glass with steam only for aircraft less than two years old and the ratio may change.
Redundancy is also on the manufacturers mind. G1000 has always enabled you to swap the PDF onto the MDF pretty much eliminating the problem of a screen fail. Both Garmin and Avidyne claim they are no longer daisy chaining critical components in their current offerings. Both Garmin and Avidyne now also include a backup solid state gyro as a standard feature significantly reducing the risk of losing a critical component.
I suspect glass will become increasingly reliable.
In the same way I guess we should expect costs to fall as this type of kit becomes standard and more people are paying for the databases etc. Certainly in terms of manufacturing a new aircraft there is a significant saving in installing glass compared with conventional instruments.
The time will come when you will not be readily able to sell an aircraft without glass unless you advertise it as a vintage or quaint and pilots will require special training on six packs - certainly for IFR ops.
It will take about 10 years I reckon.