Not within the arena of F1 they aren't.
Yeah, they are. If Ferrari were to leave F1 would die within a couple of years. Mercedes have some history, but they're miles away from having any of the romance that Ferrari have. Mercedes would only be beating privateers, as Renault and Honda would soon leave when they kept getting hammered by Mercedes, the sponsors would have already started to desert F1 and the TV audience will have preceded that.
It's a fairly bleak time for F1, and while I suppose it's not as desperate as this point in 2014, it's depressing that the manufacturers hold so much power now. It's quite staggering how quickly we've moved from the teams have zero weight (again, only Ferrari could sway things, even in their horribly bleak time pre-Schumacher/Byrne/Brawn) through to the regulators and TV companies having minimal weight. It's such a swing.
The push for a new engine or change in engine costs is effectively the FIA/FOM trying to insist they still have control, but it's not going to happen. Surely no small, independent company will be capable of coming up with a consistently reliable engine able to challenge Mercedes, and neither Ferrari or Mercedes will allow the regulations to change and possibly erode the advantage they have. We'll inevitably end up with the same engines but with a cost cap for the customer teams, which isn't going to improve the sport at all in the near future. All of this is just bluster, but I've no idea if that's a good or bad thing - I don't want the manufacturers to have control as they will protect their interests and ensure only they can win, but I don't want FOM to have control either, as when Bernie goes, deranged as he is, he's an F1 man and formerly a team owner and, often forgotten, briefly a racer, but he'll be replaced by a pure money-man, F1 will lose all of its history and identity and we'll be drifting from oligarch to oligarch.