With the amount of capacity that Qatar and Emirates are throwing at the Scottish market just now, I'd be surprised to see Cathay Pacific starting any time soon, or seeing any other far eastern long haul destination for that matter. My calculations suggest that in the high summer, there will be over 11,000 eastbound seats per week on EK/QR between Glasgow and Edinburgh alone (1 daily A380, 2 daily 77W and 10 weekly A359), and even about 9,500 seats in the lowest season (3 daily 77W, 1 daily A359). Granted, most capacity is to Dubai which is a very popular tourist destination in itself, but it's still a huge number of seats to fill for connections.
I think Cathay could have an OK chance of doing well given the number of destinations in mainland China that they serve, along with connection opportunities to Australia/NZ and I guess the UK historical links with Hong Kong, but I can't see the Scottish market being able to sustain that number of eastbound seats whilst providing sufficient yields for CX. Happy to be proved wrong though - I'd love to see them and I'd definitely use them again.