Plenty of challenges at 154 still but he should go after Chavez jr and go for a belt in a 4th weight class....
Allot would depend on how competative the fight is. Personally I would be happy to see him agaisnt Alvarez, Kirkland and any of the other young guns at Light Middle.
If he loses, he gets to go home and get comforted by his wifes massive mammaries. :hey So if he loses, he still wins.
If he loses then its time to accept the fact he is not elite and move on, Cotto V Kirkland could be fun.
Whatever he wants. Fight Bundrage for a title, fight someone else who is a name or even go to 160 for a nothing to lose fight as Martinez is old and not so big.