2020 and the Democratic Message
By 
Sarah Jones argues that Sanders has a valuable role to play in the party going forward but probably isn’t the ideal candidate in 2020:
Still, there is a strong case for Sanders abstaining from making another presidential run. The first obstacle is obvious: He will be 79 next Inauguration Day. Basketball notwithstanding, advanced age is a vulnerability for any politician. This is particularly true of a politician who inhabits the Oval Office—and this critique applies to Joe Biden and other potential contenders of a certain age.
Second, while Sanders’s campaign ignited public interest in democratic socialism, he was hardly the perfect candidate. He could have been stronger on gun control, particularly at the beginning of the primary campaign. And he too often ceded ground on foreign policy to Clinton—an unnecessary failing, considering her deeply troubling record on the issue. These are questions that Sanders will have to answer all over again if he chooses to run in 2020, and they’re a reminder that there may be a better progressive candidate out there.
And there is the matter of his fame. Name recognition is key to victory, but it can also strangle movements. Sanders the individual now gobbles up so much airtime and column inches that he threatens to eclipse the American left, to its long-term detriment. This is hardly his fault, but Sanders must now consider the broader interests of the left.
Reasonable people can disagree about whether Sanders is the best messenger for 2020, and the issue will essentially take care of itself through the primaries. (Like Paul, I agree that Bernie’s age is a real issue, although not necessarily a dispositive one. Obviously Biden 2020 is a terrible idea.) To echo what I said about health care earlier, the key takeaway here is that if only Bernie can carry his economic message, it can’t succeed legislatively anyway. The better test of his effectiveness will be whether every viable aspirant for the Democratic nomination runs on a platform comparable to Sanders’s. Gillibrand’s close alliance with Bernie after the election suggests that this is highly likely.