I think it's kind of meaningful, but that's just me.
The theory that they'd extend him for two more years, even if only one of those years is guaranteed, just to send him packing anyway doesn't quite pass the sniff test for me. If retaining him was always going to hinge on the team's results this season, why not wait to see how the season was going or after the season to do the deal? Normally when a team does something like that (does a short extension prior to a make or break season) it's to avoid the perception of lame duck status that could undermine his authority with the team which could compromise his ability to get an fair final trial. But in this case they did it and kept it secret, leaving the lame duck status hanging over his head like the sword of Damocles. That would seem to suggest this wasn't truly a make or break season for Fisher. It would suggest that at best it was only a don't completely break season.
All that seems consistent with Demoff's defense of and excuse making for Fisher and his comments that he's not being judged this season on the record. And also with Pam Oliver's report today that the team said the extension was done because they put a premium on stability. It seems like a whole lot of something for actually being nothing.