I doubt the Sox go after anyone to high end like LeMahieu since Pedroia owed $40mill for the next 3 years and he gets every chance to regain his position. As he missed all of 2018 save a couple games, there are reasons to be concerned. But I also think the Sox front office has a better understanding of his health than any of us and will address the position if they feel it needs addressing. After all, there is a chance he actually plays next season.
And if he does remain status quo, it probably gets addressed mid season like this year. Starlin Castro, for example, figures to be available.
This off-season, the Sox probably address the situation with a minor league contract like they did last year with Brandon Phillips. Phillips again is a candidate for that, along with some aforementioned names like Miller and Reyes...