Twitter trolls were 'a factor' in Hamish Macdonald's departure from the ABC
The Q&A host quit the network on Monday after less than 18 months
Stan Grant, Virginia Trioli and David Speers are rumoured replacements
Expert says 'Macdonald had an uphill battle no matter how good he was'
Ratings during his time hosting the program in 2021 less than half the 2012 level
ABC praised him for his 'outstanding 18 months with the national broadcaster'
It also noted the challenges of Q&A shifting to a Thursday night slot in pandemic
The Greater Sydney lockdown meant he had not hosted Q&A since June 24