This makes no logical sense. If Clinton or Obama or the Democrats couldn't get Ecuador to give up Assange in the first place, what influence or leverage would they have to push Ecuador to cut Assange's internet? Like I pointed out already, it isn't as if doing such a thing would even be effective, and the US government knows this. Cut Assange's internet? It would only look bad and accomplish nothing to curb any leaks because any such data would be held in multiple locations.
As for deliberately waiting to release the most damning material, that also doesn't make sense. We have already seen real evidence that demonstrates significant and long-term impact of actual scandals surrounding a candidate--e.g., Hillary's email server, and Donald Trump's profane sexism. What doesn't make sense is to do what you describe, which is to wait, because these things take time to percolate through the mainstream media, get discussed and disseminated among the voting public, and sink in and shape opinion. In the case of various allegations Trump supporters have made against Clinton, the rationale for waiting is even more patently absurd, because she isn't being accused of things that are of a salacious nature: their accusations are more deeply political in nature, and if true, would benefit more from an extended period of time to investigate their credibility. Unlike a video where it takes 30 seconds for an average person to understand what was said in a sound bite, Trump supporters' accusations would have their best impact with more time, not less, and this again is supported by the email server controversy, which they have used to maximal advantage.
So, no, I don't buy your argument. Assange is not credible; his vendetta is personal, and he lacks the standing to make good on his claims. That is not to say that Hillary is free of corruption. But there is proof that Trump is a vile and lecherous individual, by whose own admission has not paid his fair share of taxes. Put another way, I don't believe any major players in this election at this point are clean, but there is one individual who everyone can see is not only dirty to his core, he openly brags about it as if it's a selling point.