On the one hand, Hillary Clinton turned out to be a really weak candidate in 2016, and the emails would have sunk her against a strong opponent.
On the other hand, Mitt Romney lost in 2012, there's no realistic way he wins the nomination again in 2016 (Paul Ryan had a much better chance from the 2012 ticket and he chose not to run), and even if he did, it's unlikely Putin would support him against Hillary, and even with Putin's support, it's unlikely Romney could tap into the Republican base enough to beat Hillary in 2016, after failing to do so to beat Obama in 2012.
Clinton fails to carry all three of Michigan, Wisconsin and Pennsylvania, losing Michigan because of Romney's roots in the Wolverine State, and Romney being the former Governor of Massachusetts allows him to run better than expected in New England, giving him a pickup of New Hampshire.
Other than that, Clinton sweeps the battlegrounds, with the exception of Iowa, including holding Ohio and Florida.
I don't think she picks Tim Kaine here. Given Romney is a harder opponent than Trump to beat, in her eyes, she probably picks someone with actual electoral benefits, or she picks Sanders to unite the Democratic Party.
Former Secretary of State Hillary Clinton (D-NY)/Senator Bernie Sanders (I/D-VT) 50%
Former Governor Mitt Romney (R-MA)/Senator Marco Rubio (R-FL) 46%