SriLankan Airlines seems to be happy with it's Airbus aircraft and the 773ER would be too big. Btw: EK
does NOT own UL
. Emirates only has around 42% or SriLankan Airlines, the main share holder is still the Sri Lanka Government.
You could be right with the 4 vs. 2 engines. Yes, 10 seats could generate some extra revenue if the flight is full. A few month ago SriLankan Airlines had an excellent load factor on its network and we all hope that they can continue that way.
One more reason, those mentioned SQ
A340 are a few years older than the current A330 they operate. So leasing costs will go down as well.
I once heard, that SriLankan Airlines could save between 15-20 million USD a year if they replace the A330 with the A340.