Democrats will capitulate because they will always capitulate. A fundamental belief of the Democratic party is that government needs to function. They will make a big fuss but ultimately capitulate, because that is what they do, every time.
And honestly, in this case, what can they do? Holding up a SCOTUS nominee for 4 years is unacceptable. Holding one up for a year is also unacceptable, but Republicans can get away with it because their base doesn't care, and the average voter doesn't care either.
This, more than anything, makes me mad at both parties. Mad at congress for not doing their job last year. Mad at Democrats and Obama for not doing everything they could to get the nominee through. The hubris of waiting because they were confident that Clinton would win the presidency. And of course, especially mad at Republicans for obstructing and being rewarded for it. Seethes, which is a word that I've seen tossed around a lot about this nomination is exactly how I feel. I'm angry about the situation but practically there is nothing that can be done about it.