I can see 'ol Bill as the quintessential troubleshooter/skid greaser/front man/all around bush beater (no pun intended)

for Hillary, clearing a path for her to accomplish whatever agendas that were left unresolved when Bill was POTUS.
Those two paired up creates a fairly powerful entity when it comes to getting things their way.
What with the wide, solidly established networking they've long ago developed with the DC power players that make or break careers on a whim, they're going to be pretty hard to mess around with.
If elected, let's hope they use their influence and position for the benefit of all Americans and not exclusively for the plutocratic/autocratic elites that have had a stranglehold on our politicians for way too long.