Just came across this article today: JONATHAN NOLAN’S ENDING TO INTERSTELLAR MADE A LOT MORE SENSE
Jonathan Nolan’s much more straight-forward ending “had the Einstien-Rosen bridge [colloquially, a wormhole] collapse when Cooper tries to send the data back.”
So no tesseract (that was Christopher’s idea), no time manipulation, and no return home. Nolan didn’t elaborate on this point, but we might speculate that the original end to the movie was as dark and unforgiving as space.
If the wormhole collapses, that means there is no way for Cooper to get home (though the data maybe made it back to help the dying Earth), no way to find Anne Hathaway’s character, and likely a one-way trip into a black hole. It would be a classic hero’s sacrifice, which admittedly bends fewer physical laws than gravity waves ripping across worldlines embedded in a 5th-dimensional cube by some “bulk beings.”
What could have been, eh?