An agreement to bring Corsica - which has been part of the ERC and its Intercontinental Rally Challenge predecessor since 2011 - back into the WRC was inked last week, following the loss of cash from Alsace to support the Rally of France's previous event in Strasbourg.
There had been speculation of a shortfall in funds from Corsica to take the ERC back to the island and a statement from championship organiser Eurosport Events added further weight to such talk.
The statement said: "The financial situation between the ASACC [local governing body of Corsican motorsport] and Eurosport Events regarding the 2014 event is still not settled and Eurosport Events looks forward to a positive outcome."
French motorsport's governing body - the FFSA - is understood to have stepped in to bridge the financial divide to get the October 1-4 event back on the WRC calendar.
The Swiss Valais event has been an ERC regular in recent years, but lost its slot for 2015 before the Corsica move created the vacancy.
"Eurosport Events will propose an amended 2015 ERC calendar, with Rallye International du Valais as the new final round, to the next FIA Rally Commission meeting," the statement added.
Peugeot factory driver Craig Breen won the second round of the 2015 ERC in Latvia this weekend, dominating Rally Liepaja to kickstart his title bid following an early mistake on the season-opening Janner Rally last month.
After a crushing Janner win, championship leader Kajetan Kajetanowicz crashed on day one in Latvia but rejoined for Sunday and is still five points ahead of Breen in the standings.
The fifth Intercontinental Rally Challenge was the best yet, and it was Skoda UK driver Andreas Mikkelsen who emerged as champion from a tense five-way shootout at the season finale. Matt Beer reviews the season