I guess you can't wait for Hillary to lose the general election without the BernBots.
I see winning Sanders supporters as more of an opportunity than a threat. The Sanders supporters who voted for Obama in 2012 will mostly bite their tongue again in 2016. Its the ones who were apathetic before Sanders that are most likely to slip back into apathy if Sanders loses.
In other words, the Democrats aren't going to lose many voters compared to 2012 (except for possibly African Americans, but thats a different issue), but they do have the potential, if they play their cards right, to win some of the people who Sanders has gotten involved in the political process.