Spent a lot of time thinking about this topic this morning... and sadly there's just no fit for a trade for a team that needs a SS, has a quality 2B, and isn't in position to contend so they can make the trade without upsetting the team.
National League
Braves - No. Division
Marlins - No. No good players.
Phillies - No. Division
Reds - Need SS. Quality 2B, no trade fit as they can't fill one hole with another.
Pirates - Need SS. Quality 2B, no trade fit as they can't fill one hole with another.
Brewers - Don't need SS. Need 2B.
Cubs - Rich with SS talent. Decent 2B.
Diamondbacks - Rookie SS. Quality 2B.
Giants - Defensive solid at SS. Solid 2B.
Rockies - Star at SS. Struggling 2B.
Padres - Solid regular at SS. Struggling 2B.
American League
Blue Jays - Star SS. Struggling at 2B.
Yankees - Star at SS and 2B.
Red Sox - Star at 2B, need SS, don't fit.
Orioles - Need 2B, solid starter at SS.
Rays - Need SS and 2B. No good fit.
Indians - Full-time starters at 2B/SS.
White Sox - Starter at SS, need 2B. No good trade pieces.
Royals - Starter at SS, need 2B. No good trade pieces.
Twins - Need 2B/SS. No good trade pieces.
Astros - Need SS. Have solid 2B. Just drafted #1 SS last year. They're not going to fill holes by creating holes.
Rangers - Starting SS/2B
A's - Starter at SS, need 2B. No good trade pieces.
Angels - Solid 2B, need SS. No good trade pieces.
Fits
Cardinals - Need a full-time SS... but is one of their many bench guys enough?
Mariners - Need a SS that can hit... but is a challenge trade of Ackley for Espinosa a good thing?
Tigers - Could move Peralta to 2B if they traded for Espinosa, may hurt team.
Rays - Need 2B/SS. Where's the good return?
Mets - Probably best fit, but they're in division... and Murphy is an injury waiting to happen.
Dodgers - Need SS. A year of Mark Ellis isn't worth controlling the potential of Espinosa.
So, that leaves us with in house.
Lombo - Equal to or slightly better hitter, worse fielder and runner... downgrade.
Rendon - Hasn't lit the world on fire with defense at 3B. Can he handle 2B?
Kobernus - Has played some OF in AAA. Looks to be groomed as UTI player, not full-time by organization.
Rock and a hard place, it would seem.