Combine wine and lemon juice in a small pot over medium heat. Toss together both cheeses and cornstarch in a large bowl. When the wine comes to a boil, slowly add the cheese and cornstarch mixture, whisking continuously until smooth. Season with nutmeg and cayenne. Transfer to a small slow cooker set to low and serve with the selection of dippers. Fondue should hold on low setting for up to 1 hour.