You're making a strawman in this "not real liberals" claim. If anything, you are not a real liberal based on your rhetoric on this board that is absent of any leftist influence. I am a genuine leftist, as is Dochter, as are most Sanders supporters. By appealing to the fiction that a small minority of broad anti-establishment voters are somehow representative of Sanders' support, you're basically waving a white flag on the argument.
For the record, in the absence of a dead heat in the general, I will be voting 3rd party because the Democratic party will have effectively moved to the right by electing the politician that the progressive wing of the constituency was turned off by in 2008 and is even more turned off by in 2016 and using markedly rightist apparatuses in pushing her through. Your belief that "real liberal" is synonymous with unquestioning Democrat hack is absolute anti-ideological rubbish.
But, to entertain your trolling, what exactly do you think Sanders will do or what does he represent that is contrary to Obama's legacy?
Obama is more militaristic than many of his supporters had hoped: that is undeniable. However, Hillary is more so and applies her hawkishness to domestic policy in the form of her endorsement of militarizing police, expanding incarceration, and attacking the poor. The idea that Obama's legacy should be tied to inching in the opposite direction of his progress instead of leaping forward in its continuance is just stupid.
You have the stylings of a person who was born into a blue-voting family and is thus adherent to the party but might otherwise be a Republican based on your basic lack of identification with leftist policy.