I'm wondering if Soler has injured his way possibly off the team. When healthy I actually like Soler's potential quite a bit. But he has been some what fragile over his career and that has given Almora the chance to come up and potentially take his job. Basically, I'm curious about the playoffs. Almora has started hot in the majors which obviously could change but for the sake of argument let's just say he's league average which is like .257/.324/.419. If he's anywhere near that I think Maddon is going to have a tough time keeping him out of the line up. The outfield defense would be incredible. Fowler is 8th best in DRS and 4th best in UZR/150 at CF. Heyward is 2nd and 3rd in RF). You add Almora into that and it's going to give them some fairly massive range in the outfield. The cubs in general are pretty ground ball oriented but having the safety net behind you in the playoffs could be big even if it's only turning what would be a double into the gap into a single.
Getting back to Soler, Fowler is pretty safe to leave after this year. But you also have Schwarber returning. And they obviously dealt for Cogs(lefty) and Szczur is hitting .327/.373/.491 on the season and also happens to be a far better baserunner(22 SB last year 30 in 2014). So, both seem like better bench pieces in the playoffs even if Soler's a potentially great hitter. Soler is also making $3.666 mil which isn't huge but if the cubs are as cash strapped as I've suggested they might be dealing him as the main piece for whatever would open some wiggle room.
As for what they would use him to get, that's open for debate but he certainly seems like one of the more obvious players the cubs could trade. I'm still sorta partial to the idea of dealing for Drew Smyly as a bullpen piece for 2016 with the idea of moving him to the rotation next year. He has some warts on him but to be fair so does Soler and his underlying numbers are pretty good especially vs lefties. His 2 and 4 seam fastballs have been flyball magnets but Arrieta also faced similar HR issues before coming over to the cubs. If Bosio could work out some of those issues, he has a pretty dominating slider(34.9% k rate) and also not bad cutter(25.8% k rate). To me, if you're going to deal for a lefty and not go the LOOGY route this makes more sense because you at least give yourself some better options long term for the heavy price you are likely to pay for someone like Miller.
Also, one last thing on Smyly. He's got a 12.1% swinging strike rate this year which is 11th in the majors. Top 10 are Clayton Kershaw, Noah Syndergaard, Jose Fernandez, Max Scherzer, Michael Pineda, Matt Shoemaker, David Price, Cole Hamels, John Lackey, and Danny Salazar. So, pretty good indicator of TOR type stuff even if his ERA/FIP are pretty bad.