I thought 4 eng jets will be subject to ETOPS certification in the not to distant future.
ETOPS whilst currently applying to twin engine jets - covers more than just flying on 1 engine for 180 mins (or whatever limit has been applied to a fleet) - but covers cargo fire suppression, electrical generators, hydraulics etc.
I understand 747s and older types may be granted grandfather rights to continue operations as they are.
ETOPS will then be called (as occasionally as it is now) EROPS extended range operations, or EDTO extended diversion time operations.