O'Shea and Potter missed Saturday's Euro 2008 draw against Germany but both trained on Monday.
McShane is available for the Croke Park game after suspension and is likely to replace banned Richard Dunne.
Lee Carsley is also banned but Stephen Hunt is available.
Shane Long pulled out of the Republic squad on Sunday because of a groin strain sustained after he came on as a late substitute against Germany.
"I have good options in defence if Josh (John O'Shea) is available and Paul McShane is also there," said Republic manager Steve Staunton.
"Joey O'Brien also proved on Saturday that he can play in that position."
O'Shea was ruled out of the Germany game because of a leg injury while Potter missed the match because of a groin strain but both players are hoping to be given the all-clear for Wednesday's game.
Dunne and Carsley both picked up their second yellow cards of the current Euro 2008 qualifiers in Saturday's game.
Like McShane, Hunt missed the draw against Germany because of suspension.
While Hunt is available again, Liam Miller is being tipped to be given the nod to fill in for Carsley.
