Jets are very to be similar going into this season as they were last season. The main difference is just on D, where Dillon and Schmidt are out, and likely replaced in their roles by Samberg and Miller, with Heinola likely stepping into the 3rd pair LD role. They might take a bit of a step back on D, but I don't think it will be a big difference in overall quality.
At forward, I think they could have a very similar roster as last season, with the possibility that Lambert makes the jump with Iafallo or Appleton perhaps going down a peg.
Last season the Jets had some significant injuries at F, but their D was remarkably healthy. That might be the biggest variable affecting the quality of the roster this season. Another variable might be whether players like Perfetti and Samberg can take a significant step forward in level of play.
The other major difference is at back-up goalie. Brossoit was very strong, and I doubt that Kahkonen or Comrie match his performance. That might cost the Jets a few wins more directly.
Finally, I think a lot of the Jets' success will depend on effective deployment of the roster, particularly ensuring that the coaches optimize the contributions of Ehlers and Perfetti and limit the usual drag of a Connor-Scheifele top line combination creates defensively.