Brian Steinberg Senior TV EditorThere’s more than a bunch of football games at stake as the National Football League gets set to kick off its 2020 season Thursday night.Behind the scenes, four of the nation’s biggest media companies are eager to try and keep NFL football on their networks for years to come – and doing so may not be easy. The league’s current rights deal with Walt Disney’s ESPN lapses after the 2021 season, while its contracts with ViacomCBS, NBCUniversal and Fox Corp.