This is just boring tit for tat nonsense. You handwave away Clinton's inability to enthuse her support, her terrible polling numbers among independents, her terrible polling numbers in GE matchups, her consistently downwards trending favorability, you name it.
For what it's worth, I doubt Sanders will be outspent by large margins. Without going to PACs, he's keeping level with Clinton. He's raised twice as much as Jeb! so far. He'd have the Democratic party at his back, Obama and (possibly) Bill doing the meet 'n greets. He doesn't have SuperPAC access, but then... literally name a single effective thing a SuperPAC has done this campaign. They've crashed and burned.
The socialist thing is a non-starter. Everyone knows about it already, nobody cares (except you).
Sanders is just fine on foreign policy. He doesn't want to run on it, but he can talk about it.
This is not a guy who struggles on foreign policy issues.