In my opinion, the most interesting alternative timeline of Apple's history would have been had Pink/Taligent been released sometime around 1993 or early 1994, coinciding with the release of the original Power Macintosh lineup and thus beating Windows 95 to the punch by well over a year. In fact, it would have been quite revolutionary: a workstation-grade OS with protected memory, cooperative memory, etc. but installed on consumer-grade hardware; in our real-world timeline, this wouldn't happen until 2001 when Windows XP and Mac OS X were released (yes, I'm aware that the Amiga had protected memory, and yes Windows NT was around, though it was marketed to workstation users). Imagine everyday users having a rock-solid OS in 1993. Pink/Taligent would have also stolen NeXT's thunder since Pink/Taligent also provided an object-oriented development framework, but unlike NeXT, Pink/Taligent would have had a much larger install base. NeXT probably would have either pivoted or folded, and Steve Jobs would've probably been more well known for Pixar.

Then again, pre-1997 Apple courted larger companies like IBM and Sun for mergers. Apple under John Sculley almost merged with IBM; given the AIM (Apple/IBM/Motorola) alliance and also the fact that Taligent and was jointly developed with IBM, I can see a timeline where Apple and IBM merged as a way for IBM to take back control of the personal computer business from Microsoft and Intel. There are all sorts of fascinating possibilities.