Tbh I don't think January is going to be particularly busy in terms of transfers, because we have so many players out of contract in the summer it makes sense to start seriously rebuilding then. Batth's the only player in the final year of their contract to be given a new one so far, but we have *loads* of others in their final year.
Costa, John, Borthwick-Jackson, Stearman and Teixeira are on season-long loans; Edwards, Henry, Williamson, Ikeme, Saville, Evans, Price, Silvio and Ebanks-Landell are all free agents come June if nothing changes. That's 13 in total.
Of those we might try and get a permanent bid in for one of the loanees (Costa and/or Teixeira, judging from the season so far) but wouldn't be surprising to see them all go back. And of the players who are ours, Ikeme's worth keeping hold of, wouldn't be surprised to see Edwards wrangling another year extension, and Silvio's been decent so far, but otherwise it's a perfect chance to dump the Jackett-era midfield and start from scratch.
We might try and sell some of the unwanted players in January, but chances are they'll end up on loan somewhere (like Henry is now) until they find somewhere new.