I think CX actually did quite good in notifying passengers when there is a flight change or flight cancel / better than a lot of other airlines.

I am flying out to BKK from HKG in March, my outbound sector was cancelled and they rebook me to another flight on the same day and I was notified by both SMS and email. Friends travelling with me (same flight but different booking) all got the same notification via SMS and email.

From my previous experience, CX always send me SMS and email whenever there is a flight time change or rebooking. I also quite like their SMS/ email notification which sent out 4 hrs before flight departure to remind / update you the flight status which most of the other airline do not do it.

That's just my experience.