I can see this happening simply by correcting the mistakes of this season; for example, Get rid of Tebow, Revis-Holmes-Hill-Keller come back from injuries, have a McElroy as starting QB with Sanchez as backup, new OC, add draft picks to OL (Warmack) and draft Bart Scott replacement.
We need more depending on who signs and who goes but I can see a scenario where we do things differently and have a decent team.....50/50.
I don't think it's far fetched for the Jets to make the playoffs next year. If you operate under the premise that Rex will field an above average defense (even without Landry or Revis or a stud OLB). We will likely have a QB that doesn't lead the league in turnovers. We will likely have, almost by default, a better offensive coordinator than last year. We will likely have, just by getting folks healthy again, better skill position players than last year.
So, tougher schedule aside, it's not farfetched for Rex to make the playoffs next year