Am puting off some work past 2 days so I had some time to dig into the data. Looked at Yougov from August 9, 2016, the most recent Yougov, and the 2016 exit poll. Looked at the swings within each group. THe problem for the 2016 Yougov was the large number of DK/3rd parties (especially Gary Johnson, who was at 10% most of which seems to have gone to Trump in November), so I excluded all that and looked at the 2-person vote only.
tl;dr - Clinton maxed out what a centrist can do among women, black, and young people. The swing is coming from men not women. Ths data from Hispanics is inconsistent. The age trend is weirder than I thought, the boomers are equal to the overall swing mostly, the big change is 45-64. OTOH, 30-45 are stagnant or leaving the party in significant numbers.
The most consistent effect is people earning over 100k, going from a roughly even split to 60% Biden.
Specualting - Bernie would be doing much worse with 45-64 and much better with 30-44, marginally worse with 65+. Much, much worse with >100k. Marginally better with 18-29, <50k and blacks and hispanics. Overall significanly worse but probably still in the lead.