So name a top young center a team is willing to trade with #1C potential
Well first I think we'll have to say that a top young Centre with as good a chance of becoming a #1 C as Gardiner has a chance of becoming a #1 D... Gardiner definitely isn't worth the likes of MacKinnon, Galchenyuk, etc for example.
A few guys who I think might have comparable value (add small pieces to one side or the other to balance it out) and who also might be available due to depth at C.
ROR -Duchene, MacKinnon, and Stastny could make him expendable, not to mention their other forwards like Landeskog, Downie, Parenteau, etc. He obviously can't be moved until February. ROR probably has the upside to be a Pavelski type, really strong defensively, good for 60+ points.
Granlund - M. Koivu and Coyle could make him expendable, + Parise and others. They could use another PMD.
Hertl - Couture and Pavelski, /maybe Thornton/Marleau if they get resigned, could make Hertl expendable. SJ has depth on the blueline, but not in terms of PMD, especially considering Boyle's age.
Couturier - Giroux, B. Schenn, Lecavalier, and Read make him expendable. Very strong defensively, but has been given very little opportunity offensively (playing mostly with scrubs in a defensive role).
Strome - Tavares, Nielsen, and the emergence of Brock Nelson could allow them to move Strome. They have some good Dmen coming up the system, but with Streit gone, they could use a PMD right now.
None of these guys are considered to have MacKinnon, Tavares, Stamkos, etc upside, unless they really break expectations. But then again, Gardiner isn't exactly expected to have Doughty, Karlsson, Pietrangelo, etc upside himself, unless he breaks expectations.
Not all would work in 1 for 1 scenarios, but I think these guys are at least fairly close in value to Gardiner.