Already without skipper Darcy Moore (hamstring) indefinitely - and with forward Jamie Elliott (knee) out for the rest of the season - the Magpies now face another significant hole to fill in defence.
It comes after a 12.11 (83) to 11.9 (75) loss in the annual King's Birthday blockbuster left Collingwood (5-7-1) outside the wildcard finals spots heading to their mid-season bye.
Maynard first hurt his right shoulder when attempting to tackle Harrison Petty in the opening quarter at the MCG and went to the change-room for assessment.
He returned briefly, only to dislocate the shoulder again in a contest with Kysaiah Pickett, and was ruled out before halftime.
"Bruzzy's shoulder popped out twice and he's an incredibly brave player," McRae said.
"He comes back on the ground and his shoulder pops out again. But even when he came back on he was just playing tough.
"That's going to take its own course but generally we give them three or four weeks off to strengthen up.
"Young (Will) Hayes is doing that at the moment but this might be a bit more extreme than that. We'll wait and see."
Maynard's shoulder issue was one of two game-ending injuries before halftime, with Melbourne's Brody Mihocek taken to hospital for scans on his head and neck after falling head-first into the turf in a Billy Frampton tackle.
Frampton showed immediate concern for his former teammate, a 2023 premiership star who was playing his first match against the Magpies since his off-season switch.
Players from both sides went over to show their support for Mihocek before he was driven off the field on a stretcher.
"You saw our response on the field - because we love him," McRae said of Mihocek.
"There's parts of us that still would love him to be in our building and he's at a different club now, but we don't lose our love for him.
"Hopefully he's alright and supported well ... fingers crossed that it's not too bad."
Mihocek took on the Frampton tackle and was penalised for holding-the-ball in an incident McRae expects will be looked at by the tribunal.
"They're former teammates and premiership players together, and I'm watching it from afar and it sort of looked ungainly - is that the right word?" McRae said.
"I'm sure the tribunal will have its own look at it and make the decisions around it."
