The union wants to take over Newport Gwent Dragons and the ground, hoping to solve the water-logging problems by laying a 4G surface.
But  if County stay up Football League rules do not allow artificial surfaces.
"Ideally we would have wanted to put an artificial pitch down," said WRU chief executive, Martyn Phillips.
"We want the ground to be a hub for rugby for women and girls and kids and get it played on all day, every day.
"That is probably not going to be possible now because Newport County need a grass pitch.
"So we are in a dialogue with them now about how, over the summer, we put it back to what a pro club should have."
County, under boss Mike Flynn, are looking to pull of what would be  a miraculous relegation escape against Notts County, having been 11 points from safety as recently as March.
Following financial difficulties at the Dragons, the WRU has offered a deal to take over the region and a vote is set to be held by shareholders of Newport RFC who own Rodney Parade.
The rugby club, Dragons and County share the pitch which has major drainage problems that have forced postponements and abandonments this season.
County have an agreement to play at Rodney Parade until 2023 and Phillips said it would be honoured.
However, relegation would raise the prospect of a 4G pitch being laid as such surfaces are allowed in  the National League
Phillips added: "Newport County have a licence there and, despite what anyone might think, we are not in the business of wanting Newport not to be a pro club.
"We are like everyone else in that we hope they get the win and carry on.
"But the flipside of that is that the pitch is no good for us and no good for them."
The Welsh Rugby Union will halt plans for an artificial pitch at Rodney Parade if Newport County stay in the Football League.