Lyon will fall off. Detroit would be silly to sell reimer at this point

Yes Lyon's success isn't sustainable at this level for the remainder of the season but even if he drops to league average ~.903 from here on out, he's still likely cemented himself as a backup. Reimer hasn't played since mid-Nov and his last 3 out of 5 games weren't great showings (3ga, 3ga, 5ga; also not all on him, team in front of him didn't play great either in those games) for him so in CAR-fashion, he could be a buy low option that could give the Canes somewhat of a reset on the backend and hopefully get either Raanta or Kochetkov some time to figure it out for the rest of this year.

Lyon hasn’t cemented himself as a season long NHL goalie yet.

Although I am all for trading pending UFAs this season, I think trading Reimer right now would send the wrong message to the team. We don't need the cap space and if we get injuries we can easily bring up a roster player from Grand Rapids.
Although I think this is more than Reimer is actually worth, I think it would take a bit more of an overpayment to make us trade Reimer. At least that way the team could look at it as "a deal they could not refuse" rather than selling guys.
I feel they're is a ton of positivity surrounding this team right now with your they are playing. Don't think it's worth taking away from that.