It is rare for a coach to last through multiple "eras" in his tenure, particularly in todays game. And "eras" are normally defined around QB issues: either you make the best out of a middle QB with an exceptional scheme/team around him, you make the best out of a superstar QB on the cheap (either rookie deal or bargain), or you have to deal with a franchise QB sucking up a lot of cap space.
Almost every era of a coach falls under those three categories. You could argue Sean Payton had Brees on the cheap because of his contract coming off shoulder surgery when he won (so that was a great "era") but then struggled when they started paying Brees top dollar (never could get over the hump).
Andy Reid has early McNabb era, middle franchise McNabb era, non-McNabb era, early Mahomes era and now he's in the franchise Mahomes era. Again, each of those era's was a bit different.
We could argue Tomlin had "early Roethlisberger era" (when he was affordable), which is when they won, but once Roethlisberger became "franchise Roethlisberger" and especially that lockout season with no cap/first year back with a cap (in 2010/2011?), I think that screwed us and our finances (blame Colbert for that somewhat) for a long time. This team never could really win with Roethlisberger as a franchise guy getting franchise money.
But then Sean Payton couldn't win once they paid Brees. And they couldn't win up in Green Bay once they paid Rogers either. Harbaugh couldn't win once they paid Flacco. Even Seattle couldn't win once they paid Russel Wilson.
Eras have kind of "mini eras" inside them. And Tomlin hasn't really done well in any except that first era with Cowher's players and Roethlisberger still under his rookie contract (which was still manageable). Once about 2010 hit, once the finances changed (and where Tomlin was making decisions on who he wanted to keep with big contracts), the wheels starter getting wobbly on this franchise.
They thought MAYBE they had a run here the last 3 seasons, but by that time I don't think Roethlisberger was good enough or worth his "franchise" title much anymore. Took Tomlin too long.
Ideally, if Pickett is the real deal, we have a window that during his first 6 seasons, he is "cheap" or getting underpaid vs. his performance on the field. That type of overperformance vs. cost (especially at the QB position) can create a window of opportunity for a coach/GM to succeed.
That's why this era coming up is so uncertain. Is Pickett going to overperform? Can Tomlin succeed if that happens? Can Kahn?
I'm not saying it has to happen this season. But you have to hope that in 2-3 years we are good again. Maybe even really good. But that takes a lot to go right. It's why even if you don't like Tomlin, the uncertainty makes it fun to be a fan again. I think if fans were honest with themselves over the last 5 seasons, we all knew what was going to happen - no uncertainty = no fun as a fan. Now we have that again.