Arguing about what is a franchise player is semantics, and whether Seider is that is a subjective opinion. Let's assume you are biased here. Here's an unbiased, alledgedly not perfect list, but one that gives us a point of reference :
NHL Top Players: Top 20 Defensemen | NHL.com.
Seider is the 20th ranked defensemen in the league. He turns 24 in a few days. At this point, we can say he'll be a career league-average number 1 defensemen, which is great! It's a super valuable core player any team would gladly take.
My point is, though, that if a team's best player is an average #1D, it's hard to envision that team being more than solidly in the middle of the pack. Contenders usually have one or many elite players that surpass that level. Barkov, Eichel, Makar, McKinnon, Hedman, Kucherov, etc. You get what I mean.
In my opinion, Detroit is still looking for that player and they likely wont find it either at pick 14 or pick 18. I don't see anyone on their roster or prospect pool with that kind of upside, but you never know. The Red Wings do have good talent, it's just that none of them screams superstar. Their current group's upside, when all is said and done, doesn't project as a top 5 or even 10 team in this very competitive league unless they hit a home-run.
You can make that argument about a lot of teams by the way! I think the Senators, the Habs (my team), the Blue Jackets and Utah are trending that way right now too. All of these teams arguably left the basement without a bona-fide superstar prospect. Time will tell if the likes of Demidov, Fantilli, Stutzle or Raymond can elevate their team to contender status.