Define big win. Wyoming has a total of 14 delegates to divide. Sanders is projected (by the 538 site you're linking to) to win 9 of them, with the other 5 going to Clinton. This would reduce Clinton's lead to 206 delegates (from 210). Not exactly a big change if you ask me.
1) That site's projections are what a candidate would need to receive in a 50-50 national race in order to win the nomination. That isn't what they think Sanders will receive. Sanders will very likely defeat Clinton by a much larger margin than 9-to-5 delegates in Wyoming given how handily he crushed her in neighboring states.
2) It's pointless to look at Clinton's actual delegate lead. Rather, look at the numbers Sanders needs to get on that FiveThirtyEight projection and add in the 88 that he trails where he should currently be on that projection. The other 120 or so delegates that he trails her by would automatically be made up simply by him reaching the targets necessary in the remaining contests. In other words, Sanders was
supposed to trail Clinton by that margin up until this point if the race were tied nationally as the early states were more favorable to her demographically.
So, again, the magic number is finding 88 delegates to win while meeting those targets on the FiveThirtyEight page. The FiveThirtyEight target for California is merely a 2 delegate win (about a half percentage point victory, if that). If Sanders were to win California by ten points, he'd make up about 45 of that 88 delegate disadvantage and would only need to do 40 delegates better than the rest of the state projections on that FiveThirtyEight list.
I mean, theoretically, he could just slowly inch up on her and hope for a 60 delegate win in California in June with two months still remaining to build up that momentum. That's how close this race actually is in terms of
pledged delegates. The super delegate situation is irrelevant until we know who actually won the pledged delegate majority. If it's Clinton, then Sanders can just push towards the convention in order to support his message and be a fall-back candidate. If it's Sanders, Sanders sure as hell deserves to be the nominee and it will all come down to whether or not there's 300 or so P.O.S. human beings who have no respect for democracy despite their own party's name and will refuse to move to Sanders' camp.
My guess? Sanders winning the pledged delegate majority will mean hundreds of super delegates will shift to his column fairly quickly. As I've said repeatedly, why on earth they would want to disenfranchise so many young voters in favor of ones that will mostly be dead in twenty years (and for a much weaker candidate, no less) would be truly baffling. It would also completely invalidate the primary process completely as all of the money and time spent on it would have been a complete waste as hundreds of super delegates endorsed Clinton before a single vote was cast in Iowa.