Latest response from the supervisor after a response to from their team...
They said they can offer a flight on the same day that departs either 30m or 1h20 early and arrives 2h20 later so it would be a voluntary change if I wanted to move one day earlier. Obviously I said it was not voluntary as they cancelled the flight.
I'm might be able to get pretty flexible on dates as I can rebook hotels and transfers (a pain but possible with some fees to pay) so if I state that 2h20 is too late, and hence I will go the following day, can I insist on the earlier flight which would be the QR8 / QR836 under the "entitles the passenger to rebooking on a flight at the earliest opportunity" clause even if no space in "I" bucket?
Also, if they say it is not acceptable, can I just wait a few weeks / months until they change their mind or offer a AY / MH / CX option?
PS: Was told other passengers are in the process of complaining about the more restricted policy.