I’m not worried about 5 years from because I think he’ll still be a very useful player.
I'm personally not worried about 5 years from now because if they haven't won a Cup by then, they very likely will never be winning one with the current core and would be looking to rebuild again.
This rebuild accelerated when they won the Kakko lottery, who though he isn't very good now, will/should be an impact player sooner than whoever they were going to get at 8OA in 2019. It took a massive step forward when Panarin proved that he can succeed in New York and quieted the detractors (who included me). It took yet another step when Shesterkin stepped in and dominated from day 1.
All of these things have changed the timeline. At the end of last season, the question was will Kreider still be good in 5 years when this team is hoping to compete for a Cup year in and year out. The question now, in my opinion, is who is going to replace Kreider's production, and yes, intangibles, over the next few seasons as this team tries to compete. Kreider's usefulness aligns with this team's timeline now, rendering those out years less critical a concern.
All of that said, I still think they should trade him, but only if they have reasonable certainty and a willingness on the player's part to come back. If he can land a premium asset or two as a rental it is helpful in multiple ways:
1. Pushes this current team farther up in the lottery. They are not winning the Cup this year, even in the highly unlikely event they sneak into the POs. Finishing three points out of a playoff spot this year won't be good for anyone.
2. The assets received in the Kreider return, along with our own pick that's a few spots higher than if he stays and continues to produce, can be packaged along with other assets to get an impact player that is ready to contribute next season.
Off we go.