Bit of an update on this. The agenda for the Combined Authority meeting next month contains a number of documents relevant to the proposed franchising scheme.
https://democracy.greatermanchester-ca.gov.uk/ieListDocuments.aspx?CId=136&MId=2678&Ver=4
It looks like the audit has been completed and between October and January they will undertake the consultation with stakeholders.
It is proposed that franchising will be brought in in three phases - contracts to be let in 2021 for an area roughly comprising Bolton, Wigan and Salford, 2022 for Oldham, Rochdale and the Northern half of Manchester, 2023 for South Manchester, Tameside, Trafford and Stockport.
The list of services included in the scheme appears to only include routes wholly within Greater Manchester, so there's going to be a lot of routes needing a permit to continue operating.