What could have been ? Everything.
The iPhone could have been invented a 100 years ago, and today we’re missing things that can happen today but will not for another 100 years.
There are simply too many possibilities - too many alternative futures and outcomes, and chance (or karma?) selects one of them at every moment - paving the way for the next link in the chain, and the next.
It takes a long time to build these chains, which is why destiny seems so forgone, so inevitable. Because the chance event that started one chain rather than the other has long been forgotten by the time its consequences become clear. And when we trace back the links of a chain in an effort to deconstruct it, all we are left with are the links which are so recent and so obviously on a certain path that they look inevitable.