Having won the group, we don't have to even think about CL again until the 18th of February at the earliest. That's 84 days from now, nearly three months.
I would hope Sane and Laporte will be well near fitness, and so should Zinky who gives us some depth. I would also hope we get deeper at CB in January, though I have no idea who we can get of quality who isn't cup-tied.
Hanging close with Liverpool (not to mention others) with our current side is going to be difficult. Healing up and improving by mid-February to be ready for CL gives me a lot more hope.