Is it possible to do a Mod incorporating the whole world.....

Rather than just Europe and the Americas even though other lands are not discovered yet can we include places like Asia, southern Africa and Australia in a mod so that you can explore these lands ahead of actual history.. Maybe adding a few factions for them like the Chinese/Japanese/Natives etc.

You'd need at least the Persians and Chinese,. India at this time was acollection of probably 100 different little nations.

The issue would be one of balancing the game versus reality. There is no really good reason why China couldn't have conquered everything from just beyond the Great wall to the other side of Hadrian's wall. other than they couldn't control their own population. The huge distances don't seem to matter as much in a game as they do in real life when you might even be talking of multi-generational armies.

There would need to be some form of the bigger you get the more chance of rebellions system in the game

As far as I can see the main concern is the maximum size of the map, which would have an effect on long-range loyalty - that effect being that no range in-game would be long enough to cause a serious enough effect, even though there are negative effects caused by the distance of a city from the capital of that faction.

Even using the maximum dimensions you would still need to radically simplify the map, perhaps too far for your aims to remain the same. I'm all for such an idea, which would be a HUGE project, but I think perhaps the hard-coded limits will get you in the end. Also, it must be considered that the map is not a sphere, so the Japanese would have to get to America, and vice-versa, not through the pacific but via the Indian and Atlantic Oceans.

i think theres a hard coded max number of provinces

Which is only partly relevant to the question, but nonetheless true. The limit I've seen bandied about is 251 or somesuch, for Rome, though that may have been increased in MII.

You could make such a map, but I think that the gameplay would be rather strange without some way to reach the Americas from East Asia across the Pacific (some kind of teleport script perhaps?).