I think you might be overestimating Hibbert's current stature. He's more punchline than legend at this point, and for all my interest, there is an uncomfortable element of overpaid scrub getting overhyped because of one big playoff series, reaching for respect...and then coming crashing back down to earth and losing it all just when it was within reach. He's the least productive max player in the league. Having he and Bynum together there is ironic in that way. The real question is just to what degree he is the Indiana defense. If he gets hurt tomorrow does it dissipate? Or do they have enough personnel, and enough of a culture, that he can be swapped out and it will still be stout.
I've looked at Indy's financials for next year and if they really wanted to they should be able to let Turner walk, resign Stephensen, assuming nobody drops a ridiculous offer on him, fill out the roster with minimum contract scrubs, and go at it again while just barely scraping in below the nex luxury tax limit (the unexpectedly large bump was a godsend for them). But they've got major chemistry issues and are one game from imploding in ugly epic fashion leaving a stench in the Indiana air that is not going to dissipate all summer. Hard to see them just shrugging, and saying stuff happens. I would imagine a fairly significant shakeup of some sort is going to take place.