I have done some research and i have found 3 similar trade that involved a young forward that still are RFA.
1. Ryan O'reilly 24 years old coming off a 64 and a 55 point season.
Col got 2 of Buffalo best prospect and another one in their top 10 in Comtpher and a second round pick
2. Phil Kessel 22 years old coming off a 60 point season (36 goals)
Bos got 2 first round pick (that have become Seguin and Hamilton) and a second round pick. Boston got lucky with those first round pick as Toronto was trash for the nest couple season.
3. Tyler Seguin 22 years old coming off a 67 and 32 points (in 48 games).
Bos received Reilly Smith, Joe Morrow (23 overall), Matt Fraser and Loui Erickson who was the main piece (Who had 63, 71, 73, 71 point the prior year)

now Dubois will probably get something similar to those players. make your offer!

Who said the Seguin deal was fair tho?

Kessel is a winger, not comparable. Seguin trade was brutal for Boston (hence why you shouldn't trade young stars for anything short of a ridiculous overpay).

The team that traded the best players are almost never getting the value back Historically. the best chance on a trade like that is a 1 for 1 trade. You can still get lucky like Colorado or Ottawa and got a lottery pick with the draft capital. But overall the team that loose the best players won't get equal value.