Could this just be a database mess up and my original flight is indeed flying?
For a flight scheduled in January, especially a Cathay Pacific flight scheduled in January, anything is possible.
Can I assume that Cathay won't make any further cuts to their Vancouver schedule?
I think making assumptions about what happens 4 months from now is undesirable.
wait for the flight to get officially cancelled and then try my luck with Cathay being able to move me to another flight? Is that expecting too much from Cathay?
I don't think it's generally too much to expect from Cathay but it's not guaranteed.
If you want to increase your chances I would suggest double / triple booking refundable flights to your desired destination and cancelling closer to when you intend to fly.