29%.
She would have no major accomplishments to her name whatsoever, constant investigations into her administration, stalled nominations for countless cabinet and judicial positions. It would be a mess, to say the least.
A Hillary win could have resulted in a 50-50 Senate, depending on what this hypothetical win is based on and how wide her margins are in certain states. There is certainly an argument that with a slightly bigger national PV win, Kander and McGinty wouldn't have lost. All Kander really needed was for her to not totally implode there, and McGinty just needed Clinton to carry PA even semi-comfortably.
But she would still be obstructed at every turn, and thus no accomplishments. Investigations in the House would have been plentiful as well. I don't think she would have been in as bad of a place as Trump, but she would still be faring bad historically. Maybe low-mid 40s, with only further to go by 2018.
