I'm going to age myself with this response, but I fully believe Bernie needs to win. The Republicans and Conservatives have had their way since 1980. The Democrats have had I think two Presidents in that timespan and the Republican party has gone WAY too far to the right and worse, it's split itself up into way too many demographics. This creates too many potential candidates for the party.
I'm a Bernie Supporter but I'm fully aware he isn't going to make the whole world free. I'm fully aware that he is very, very old. But I believe the Conservative Republicans have stunted our growth by preventing the minimum wage from rising and allowing corporations to not give out enough of what they are taking in and instead keeping most of it for themselves. Our economy has seen short bursts of growth since 1980 but more recessions in that timeframe than from 1940-1970. My expectation for Bernie is to be a one term President, ignite the political fire of my generation, end Citizens United and raise the minimum wage.
I believe his Presidency will do one fundamentally great and important thing. It will split up the Republican party. The Republican party will eat itself apart and people like John Kasich and maybe even Chris Christie will split for the Democratic party or declare as Independents. This will pull the Democrats closer to the middle while pretty much abolishing the Republican Party over the next 4 years. I think you would see the next election be between Kasich-Clinton-O' Mallley and hopefully Rubio splits as well. I think the Republicans would counter with trying to prop up a guy like Bloomberg or being more supportive of Christie and the election being between Kasich-Clinton-O' Malley and Christie-Bloomberg-Rubio. I personally hope Rubio switches sides and the race is really Kasich-Rubio-O'Malley and Christie-Bloomberg-Paul.
The problem for the Republican Party is that instead of coming up with a Conservative solution to the problems we have at hand, they deny the problems exist. I think a guy like Sanders needs to win so then both parties get drawn to the middle.