100 new aircrafts is certainly a number beyond company's capacity and mostly because of the structure of training which is required by GACA
This talk has gone on for a few years, the company requested the aircraft from the Government and are awaiting approval, as you said the original 777-200's were delivered starting on the 25Dec1997, there are 22 of them and most of the A320's are leased, so they can easily change 50 aircraft without needing to hire any crew.
I doubt that the E170 needs to be replaced by a 90 seater, economically the 320 would suit as the domestic loads are high with an ever growing population.
As for PSAA, well what can I say
