PIA is SYD bound - interesting once weekly, with aircraft overnighting... be interesting to see how they last.
It will be interesting to see if SQ take a hit on numbers with this, and to a lesser extent MH, TG and the Middle Eastern airlines. With one flight a week, I expect not too much, but if it takes off (pun intended), who knows! I don't know how big the market is either. Just rambling here ...
I don't think SQ has serviced Pakistan for many years. They ceased services there a number of years ago following concerns about providing safe locations for overnighting crew in country. ME3 didn't have to worry about this as they could turnaround and operate the return service with the same crews.
SQ first started flying to Pakistan in 1985, SQ417/418 SIN-KHI twice-weekly using the 747-300. Taken from the History of PIA forums.
Then a 5th freedom tag-on was added to DHA (now DMM), and the 743 was replaced by an A300. Later this became an A310-300 to DXB, then a 747-300/A310 split (with the A310 only operating the KHI-DXB segment), then back to the 747-300. Sometime in the 90s it became a SIN-KHI terminator with the A340-300, and a third weekly frequency was added.
In 1999, the flight became a four-weekly SIN-KHI-LHE-SIN triangle route (SQ418) In late 2000, the A340-300 was briefly replaced with an A310 again due to construction work at LHE's runway. The 777-200ER briefly operated the route in early 2001.
The route was suspended after 9/11, specifically on 28th Sept 2001 (date taken from SQ's 2001-02 annual report). It remained suspended during the invasion of Afghanistan and the India-Pakistan nuclear standoff, then was restarted as a three-weekly 772 service on 2nd Feb 2002, but lasted all of three months.
On Wednesday 8th May 2002, a suicide bombing hit the Sheraton Karachi, which was the SQ crew hotel. Although no SQ crew were injured, 2 Pakistani civilians and 11 French military advisors were killed (they were in Karachi to help design an Agosta-class submarine for the Pakistani navy). In addition, the blast was close to the Pearl-Continental Hotel, where NZ cricketers were staying during their tour of Pakistan. The Black Caps' physiotherapist Dayle Shackel got a small cut on his forearm from flying glass. Needless to say, SQ pulled out of Pakistan, the Black Caps abandoned their tour, while the Aussies' planned tour was moved (1st Test in Colombo, 2nd/3rd Tests in Sharjah, as mentioned before).
It would be four years until SQ returned to Pakistan, another three-weekly SIN-KHI-LHE-SIN triangle route with the 772, but now renumbered SQ460, from 1st Feb 2006. Surprisingly, SQ kept flying the route even after the Islamabad Marriott hotel bombing in 2008, but reduced frequency to twice-weekly. It would be the GFC and increase in sectarian violence in Karachi in 2009-10 (the reason CA cancelled its second crack at a tour on Pakistani soil in seven years) that finally ended the route for good on 17th Feb 2010. SQ hasn't been back to Pakistan since, despite the large Pakistani community in Singapore. MH left in 2012, while Cathay left in 2014 after the KHI attack, so the only Asian connections to Pakistan to this day are via TG, UL, Air China or backtracking on the ME3, probably because they're close enough that they don't need to overnight in ISB/KHI.
I don't believe SQ ever flew to Islamabad.