The good news is that he’s participating in some baseball activities, having hit off of a tee yesterday and started throwing (Cubs.com). It’s not inconceivable that he could be ramping up to full batting practice and outfield throws relatively soon.
It remains an open question, however, how Soler would be used upon his return. If everyone else is healthy, you’ve got to assume that, against righties, the primary left field option will be Kyle Schwarber, right field will be Chris Coghlan, and second base will be Javy Baez/Starlin Castro/Tommy La Stella. It’s possible Soler would work into that rotation against righties – his upside remains significant, and he was hitting very well for the month or so before he went down – but it’s also possible he would primarily play only against lefties.
Even in that scenario, Soler could only find a spot if multiple players from the Schwarber, Baez, Castro, and Austin Jackson contingent were sitting (for example, it’s not hard to envision Jackson playing for Schwarber, Kris Bryant sliding to the outfield, Baez playing third and Castro playing second against most lefties). It’s possible Soler starts periodically through the end of the year, and then has a chance to reclaim a full-time starting job next year once the roster is re-situated and the infield is a little more settled.
For what it’s worth, in 20 Cubs plate appearances, Austin Jackson is hitting .278/.350/.389, and he’s been crushing it to the tune of .373/.409/.554 since August 12.