With QPR having slipped out of the Premier League in 2012/13, France international Remy was not expected to hang around for long at Loftus Road.
A season-long loan was arranged with Newcastle United, allowing him to step back up into the top flight.
Remy has impressed for the Magpies, netting 13 times in all competitions, and is drawing admiring glances from 'big clubs' across Europe.
Redknapp expects a sale to be sanctioned this summer, regardless of whether he takes QPR back up, with a £10million release clause set to be triggered by a side competing at the very highest level.
He said in the Fulham Chronicle: "Remy wants to play Champions League football next season, so they tell me.
"The chances of us keeping him are not great if he's got a buy-out clause.
"He's done well at Newcastle, and one or two other big clubs are trying to get him, so there's every chance he will go.
"I chased him at Tottenham, and I knew he would do well.
"He's a scorer, and with the right team pushing to get in the top four, he's capable of getting 20 goals.
"If I say he's worth £20m and his buy-out clause is £10m, or whatever, then it's difficult."