Keep in mind the source - Piquet Jr. I would bet that if Piquet was really a close friend of Alonso's, he wouldn't be spilling a bombshell like this to the press, and if he's not a close friend, I doubt he is privy to what is going on in Alonso's mind.
33 is not over the hill for an F1 driver anymore, and he must have known even when he first looked at the Mclaren/Honda deal that he would need to commit for the long term to see any chance of a WDC.
My take on this is somebody asked Piquet what he thinks
might be going on with Alonso at the moment and he simply gave his opinion. Nobody knows better than us that the break between the season opening fly-aways and the European season always makes the journalists hungry.
That said, if Alonso is seriously giving up on F1 simply because he and his management have made horrendous choices over the years, well I won't remember him as possibly the most talented driver F1 has ever seen (as I think of him now), but as a quitter with poor judgement. Put your head down, work hard and stick with Mclaren for at least a few years. Then go and join RBR and try again.
http://www.bbc.com/sport/0/formula1/32503163