It's clear that the likeable Brazilian will not be beating Fernando Alonso any time soon. The Spaniard has been quicker, more consistent and has managed to get Ferrari to build the team around him.
Massa's performances over the past 2 seasons haven't been good enough to justify him continuing his career in a car that good. I think he will have 1 more year at Ferrari and then will be asked to move on. There are a few drivers that could be a good bet for that seat - Nico Rosberg, Robert Kubica and Sergio Perez.
However, I can't see a career path that Massa will be able to take. Maybe he'll replace Kimi/Rubens at Williams, Ross Brawn might renew his relationship with him at Mercedes. Renault and Force India are also options. However, it's clear that he's unlikely to find himself in with a chance of winning a championship again and this is a great shame.
It's easy to forget that in 2007 and 2008 he had some performances similar to Vettel's domination this year. Of course he made a few mistakes at the time (I remember people wanting him to be kicked out of Ferrari after 2 retirements in the opening 2 races in 2008) but some of his drives were supreme and he could have been a champion. Maybe if he had managed to win the 2008 title then things would be massively different for him.
Unfortunately I don't think he'll win another race in F1, there are too many strong drivers around him now. His favourite circuit, Turkey, is no longer on the calendar either.
No-one who has come so close to winning a title has never managed to make amends on another occasion. Unfortunately this is what will happen to Felipe Massa - so close, but not quite.