I agree with your 3 highlighted points, it wont work until those managers and ex Aviance staff have gone. Until then it won't work. I think Dnata are running the ramp business down so they can get rid off dead wood staff and management, then rebuilt there business from scratch.
Menzies won't be the handler for Star Alliance contratcs in T2 as they have just lost Air Zealand, TAP, Aegean and Asiana as from spring 2014. Thats confirm from a Menzies employee it was on there notice board. ASIG is taking over the ground handling for those airlines..
Air Canada will self handle in T2. DNATA have 3 Star Alliance contracts as it stands what happens to them who knows.
At the the moment there is a lot of rumours flying around.