IF the eras aren't enough (and I really think we need to make sure of this first), then yeah I think what you're describing, ie. some kind of "hybrid" between the two, is probably the best bet.
On a practical level, the era information is just a bunch of
these templates spread out all over the wiki. As I said, switching to a completely different system would mean every page with one of those templates would now need a new template, and that's a scary amount of work to make happen.
But what if we could "build on the existing infrastructure? What if, as you suggest, all those template tags could take one more "argument" of a patch number or date (we need to figure out which is better, which depends on other questions like "how exactly do we want to store patches in the wiki?", since this thread has already made it clear the "/Timeline" page isn't good enough).
If we did it that way existing pages would keep working as they do, but then when someone motivated (like you) wants to make them
more detailed, they could just edit the code and add the extra argument.
I'm not ready to commit to anything personally yet: this is big and important and I want to get it right, and to do that it would help to think through stuff like how we'll do the timeline/patches ... but I really think you've identified something we
likely will have to address, and you've identified the best (ie. hybrid) approach to doing so.