If Strickland loses to Portman, he can:
1) Run for Ohio governor in 2018 (He could beat Mike DeWine or Jon Husted)
2) Run for Ohio's 6th congressional district again against Bill Johnson (Romney won that district 55-43).
(Trump may overperform Romney there due to his white working class appeal)
3) Run for DNC chair in 2017
4) Cabinet position in a Hillary Clinton administration
5) Liberal think tank
He's 74 right now and will be 75 by the time of the election. If he loses to Portman, this is his last hurrah.