I think it's safe to say the 9/9A are pretty much confirmed, 7/7A is a surprise (if true), but i guess it makes sense given that most of the other main routes around it have new, nearly new or refurbished stock. Plus the 7/7A/75 somewhat interlink as they provided a combined 5 minute frequency during the day (15 minute evenings).
But that's only a small section at the end of the route, cutting it could potentially lead to a decline in use making it less reliable, it could also cause capacity issues further towards the city centre. Agree with the 9/9A though, getting new vehicles for it entirely makes sense, especially given that it currently uses the somewhat worn out B7RLEs and is in direct competition with the McGills 38, although i suspect it's more friendly competition as the MDs of either company seem to get on fairly well...