Worst season in recent history. Cars were disappointing and only one team had a chance. Hopefully the other teams get back in the game next season.
Next year, the only other team that might be competitive is McLaren Honda... but even that is highly unlikely.
Williams is the next closest but they're a customer Mercedes team, so they'll never be as good as the works team; but they can definitely come close and be there if the works team has a mechanical failure.
For 2015, there needs to be a unanimous decision among the engine manufacturers for there to be a regulation change. It's in Mercedes best interest to keep the engine frozen for the next decade. Having said that, they've agreed to increase the number of engine token changes. So very specific parts of the engine can be changed, but it's very limited.
In 2016 regulation changes only need a majority decision rather than a unanimous one. Teams like Red Bull have even suggested going back to the V8 engines; Mercs/Honda have responded by saying they'll leave F1 if that happens; the problem is sponsorship, it's easier to sell hybrid/green technology that's relevant to the future of road cars.
Although a lot of people want competitive Ferraris & Red Bulls; the problem is cost. Ferrari & Red Bull (Renault works team) are more than happy to spend an unlimited amount of money into engine development. It ends up becoming a spending war, and the customer engine teams simply can not afford the engines; the sport becomes unsustainable, and the smaller teams like Williams, Force India, Lotus and Sauber will have no choice but to leave; and we're left with five car teams of Ferrari & Red Bull.
A big concern with F1 is cost caps, and controlling them. It's one of the reasons why Caterham and Marrussia are gone.
At the end of the day, Mercedes pulled a rabbit out of the hat with this new formula 1; Renault (Red Bull) & Ferrari had the same opportunities as them and completely blew it. 2016 is a bit of an unknown right now, but don't expect a competitive Ferrari or Red Bull until then.
The other teams are expecting Mercedes to dominate again next year. But finishing second or third in the constructors championship still gives them a lot of commercial/tv-rights money; more than enough to continue racing.