I think it's highly unlikely that there is 2 rookie d-man in the line up next season, like you wrote "Instead of bringing new kids Yzerman brought bunch of plugs to improve team and try to make playoffs." Same story next season.
X1 - Larkin - Ray
Cat - Comp - "Kane"
Fabbri - Veleno - "Sprong"
Ras - Copp - "Fischer"
Kostin
Walman - Seider
Ed - X2
Chiarot - Petry
Määttä/Holl
Lyon
Husso
X3
X1 should be Berggren replacing Perron, for next seasons success it would be important to re-sign Kane and Sprong. Fischer has played well, i would re-sign him, 1-year deal. Re-sign RFA forwards and offence is pretty much set. 50-game mark is closing and Wings are still in the top-5 in most goals. No point to blow it up.
Danielson starts in GR, no point to even expect that Danielson starts in Detroit. The brass finds a excuse, no matter how well Danielson plays in pre-season. "Not enough center spots in the top-9" or something like that, without any injuries it's not happening. Kasper is now roughly where Ed was last season and he had to return to GR this season. After next season Fabbri will most likely be gone, that opens up a spot to Kasper, Mazur or Danielson. Veleno takes Fischer's spot, Fischer's could take Kostin's spot, i don't see much use for him. That would open a 2nd spot, two best gets in and worst goes to GR.
X2 will be intresting, re-signing Ghost is one option but it should be short term deal. Trade imo would be best choice, there's been that hfboards rumour that Yzerman is trying to make another "McDonagh"-trade. Everyone here been after Hanifin but Wings are set in LHDs, RHD would make more sense. Ekblad would be perfect, i don't see Florida having the cap space to re-sign him. Florida is a short of D prospects, which Wings have plenty. I think it could be done. UFA pool quite poor, but that probably is the last resort. Or then Yzerman keeps Määttä. Johansson will be the 1st call up, unless he gets traded. Which seems more likely, i don't see a fitting role in a long run.
X3 is probably "Lyon 2.0", Copley? Rittich? Or maybe Reimer re-signs a cheap deal.