Edited Oct. 19, 2020 at 9:25 p.m.
That's a hard pass from Detroit. The 2021 first is very likely to be top 5 again. Danault is a good 2C sure, but adding a 4th and two lesser prospects is not worth a top 5 pick. Considering that Danault isn't going to be happy with playing 3C, that would decrease his value even more.
Also FYI, the oldest core player Detroit is building around is Mantha, who is 26. Danault is 27. Detroit's average player age is high because of depth players over 30 years old (Nielsen, Helm, Filppula, Biega, new additions Staal and Ryan, etc.) Detroit is not an old team anymore, they don't need to get younger.
On a different note, I think it would be a terrible move to trade Danault right now anyways. KK and Suzuki are 20 and 21, respectively. They're almost guaranteed to have growing pains in the near future, and keeping them in the Top 6 while having those struggles will hurt their development and confidence. Keep Danault, move him up to the Top 6, and let whoever is struggling play against lesser players to work through the struggles. If KK and Suzuki can make it to the deadline with minimal issues, then trade Danault at the deadline for a premium.