Obviously the loss of one powerplant on a multi eng A/C is all about loss of performance & system degradation, the latter usually taken care of by by multiple redundancies built into 2day's modern airliners.
Any decision based on the above to continue a good commander takes into account all the possibilities going on or returning to either the Dep drome or an Alt drome.
'Peuce' sums it up well, every Eng failure is diff.
Commercialism is also taken into account but should be the least featured thought in a commander mindset.
Even heavily monitored engines can fail & do unexpectedly after all they are machines designed by the hand of man & therefore subject to failure.
Wmk2