(I should preface this by saying I've only been following PSU football since 2006. I never cared a lick about college football until my HS' star QB, Brett Brackett, committed to PSU. I immediately fell in love with everything about the institution and graduated this past May. Feel free to "get off my lawn you whippersnapper" me in the comments.)
The pessimism begins. We've been spoiled with the most stable coaching staff in the country since before I was born, and now we're in uncharted waters. We're scared it might end poorly for us, and it very well could. Our on-field performance could easily suffer directly due to coaching deficiencies.
But more about pessimism. Pessimism has been something that's pervaded our entire fanbase as long as I've been following Penn State football. I've tried to figure out why the past couple years, and it seems pretty simple to me: PSU fans are pessimistic because we've always gotten what we expected, and we expect what we've always gotten. The last 5 years, our expectation has been to come out flat in just about every game. And when an equal or superior opponent capitalizes on this, we've lacked the willingness to move on to (or maybe even prepare) a Plan B. The game is over by the 3rd quarter. I haven't run the numbers, but a casual glance at our schedule/results the last 5 years shows an astoundingly low amount of close games. *
This is why I'm generally optimistic about the coaching search, and why I'll throw my support behind whomever Joyner hires. I can't wait to watch something new on the field. I'm excited to start experimenting, to potentially see drastically different looks. I'm excited about maybe seeing some man coverage. I'm excited to start making game-plans mold to the players and exploit matchups. I'm excited that even if next season is a disaster, the headaches will be different (and, we'll have a handy excuse!). I'll give a pass on a few bad seasons if it actually looks like the staff is trying. The only way I'm going to be dissatisfied with a hire will be if the new coach tries to mess with our tradition and history. I don't think that's going to happen. As badly as the top admin has been handling the Sandusky crisis, I just don't seem them hiring anyone without making sure they'll be loyal "to the brand".
TL;DR - Change is scary. Sometimes, change can be bad. But change is never boring, and that's why I'm excited about the coaching search.* Note - There are a few exceptions, especially this year. And I know it's been argued ad nauseum on this site about what expectations are reasonable, what constitutes success, how you shouldn't get frustrated by losing the games you're supposed to lose, etc. I'm not trying to start this argument up here. There's a large portion of the fanbase who's been frustrated the last 5 years. You might be one of them, or you might think they're crazy. But they exist.