First I would fire the coach and GM. I would hire a president of hockey ops to fill in as interim GM till we find one.
We need to see whether or not this team can have any sort of success under a new coach, if they can't then the group as it is isn't cut out.
If this group can't pull it together as we near this trade deadline then soft rebuild. Keep everyone under 25ish. Trade everyone of value over 25ish. Accumulate picks and prospects for your players of value like Miller, Horvat, Boeser?/Garland?(if you don't decide to hang on to them). You don't have to trade every veteran of value right away this season but guys like Miller and Horvat are at their highest value now. You'd be shedding cap space at the same time, try to stay near the floor. Draft top 5 for 2 years with our own pick then start to build your roster with the high end youngsters you draft, the prospects you traded for and the rest of the holes on the roster via free agency with the cap you cleared.
You wouldn't be a playoff team right away after the 2 year soft build with youngsters on the team needing time to grow and perhaps you can't fill on the holes on the roster in one off-season(that's a big ask) but you'd be on the uptrend.