On this site I've seen many comments about the inevitability of Hillary Clinton as our next president. From Kos's numerous comments peppered throughout his diaries to Armando's recent front page diary (http://www.dailykos.com/... sorry I still dont know how to link to things). I disagree with the hypothesis that we should be more like the Republicans who have built a grassroots machine to force their issues into the forefront. And that we should only advance "lower-profile candidates who is not perceived as a threat to the frontrunner". This type of complacency is not what is needed to advance progressive causes. We do need to fight for a progressive president if only to do what Bernie Sanders is proposing and push the debate to the left.
The statement that we should be more like Republicans in terms of our political strategy is odious at the outset. It's also demonstrably false. Firstly we have elected plenty of progressives at all levels of government. The congressional progressive caucus is the largest group within the Democratic Caucus, currently at 71 members. For reference the Tea Party Caucus is 53 members. Yet the Tea Party clearly wields more power than the progressive caucus. Why is this? Well simply because it's easier to get what you want if your governing philosophy is to stop all government than it is if you actually want to try to do some good. If the progressive caucus were to simply say we are not going to vote on anything unless it is 100% what we want then they too would accomplish something. But this is not what Democrats do. Democrats negotiate to get the best possible thing they can actually pass without destroying the system of government itself. Whereas the Republicans goal is the actual destruction of our system of government.
So how do we actually get good things accomplished in a climate where one party is proud to be intransigent. Well we do the best we can by electing the most progressive people into every possible position we can. This includes the presidency. The president does have the power to get many things accomplished even without the Congress (our current president just isn't that eager to do that because of his belief in our government, but Bush was before him). Progressive principles are clearly more favored by people when they are actually spelled out. So the argument that a third-way Democrat is more electable than an Elizabeth Warren or a Sherrod Brown is simply not true. The third-way Democrat might be more charismatic and that might be what gets them elected over the progressive but it is not because their positions are more desirable to the country as a whole (they've just made their positions more palatable to the country as a whole).
A prolonged primary only hurts the chances of the actual candidate if what they are saying is anathema to the general voting population. This is true for the Republican ideals but not for the Democratic ones which are populist in their nature. So we should not invoke the Republican policy in this case but stick to the Democratic one (the Republicans seem quite eager to shorten their primary process and cut down on their debates we should not copy that).
So I think that yes we should encourage Bernie Sanders, Elizabeth Warren, and anyone else who would challenge Hillary Clinton to step into the race.