Chase looks certain to return to St George Illawarra, who are also being linked with his England team-mate Gareth Widdop, and Castleford chief executive Steve Gill says the club "will deal with the matter" after the fourth-round tie at Headingley.
"Could it be his last game, potentially yeah," said Orr, who has stepped in as caretaker coach following the departure of Ian Millward. "I honestly have no idea. All I know is that Rangi is 100 per cent committed to the club and he'll be playing tomorrow night."
He added: "With Rangi, no matter where he goes there is always speculation and rumour and there's always people either patting him on the back or having a go at him.
"He's accustomed to all that, he's used to all the pressures that come with being Rangi Chase.
"He's a key player for us, everybody knows that. He's a big part of what we're trying to achieve here and for us to do well we need Rangi to do well. He's aware of that."
Orr is able to recall Australian winger Justin Carney following his two-match ban, while second-rower Lee Gilmour, who won the cup five times with Bradford and St Helens, is back from injury.
Leeds, runners-up at Wembley for the last three years, are close to full strength as they look to maintain the form that has brought them a five-match unbeaten run in Super League.