Trump Used Goldman Sachs Against Cruz Today
At his rally he framed the fact that Cruz did not report his loans from two major banks (GS included and mentioned specifically) as an act meant to hide from the public the fact that Cruz was essentially owned by them and in their pocket (unlike Trump of course, who specialized in buying politicians himself). Later Palin reinforced the message that unlike anyone else running for President (conveniently ignoring Sanders) only Trump could take on the establishment that owns both the Democratic and Republican parties, because he doesn't need their money. Therefore, for example, it was stated that Trump isn't forced to support trade deals that are bad for most Americans.
It's not hard to see what one of the major attack lines will be if Trump ends up running against Hillary. And no I don't think Trump needed Sanders to point to the fact that Clinton has received large sums from Goldman Sachs. It doesn't take sophisticated Operation Research to come up with stuff like that.