Yeah think about etops quite legal to operate upto 3 hours from a strip on a single. Economically the same arguement suffices, cheaper and more efficient ops with less engines. 777vs 747. Seneca vs Caravan. It is now commonly accepted that turbine reliability is no longer a problem, its more likely fires, or electrical problems.
Heck i beleive that the day is near where by there isnt a restriction time on an aircraft to fly on to its destination on a single engine.
Only problem i can see is convincing the public and their perception, the old hand pilots who have never had to deal with flying a viable single as opposed to a light twin , and the regulators. The regulators are under huge pressure from boeing and American's in general as to accept these twin engine aircraft or face finanical ruin.
I cant see cessna having much weight to their argument to allow further changes to the rules.