>> As an example, Lufthansa recently used jumbo jets on the domestic Frankfurt / Berlin route after their competitor Air Berlin went belly up.

Color commentary: This is a outcome of a micro trend that was caused due to the collapse the 2nd largest airline in Germany. It is unlikely this is an indicator of longer aircraft deployment. Regional and domestic routes tend to skew towards frequency and convenience. Most major airports and regulators also encourage this behavior when analyzing and distributing airport slots.