Size does matter. (size of single map?)

As expected range of supported map location is -2,147,483,648 to 2,147,483,647. ie. longint. If i remember correctly marked grid size in editor is -200k to +200k. So we can place 10000x10000 editor grids in that area, it is huge. Also resizing skybox to that size (or even 4, 5 times bigger) surprisingly works (however i resized it more and there were funny artifacts). But it can be big enough to not have paralax effect even on edge of known universe (ie max int location).

Now i have few questions:
does physics and network replicating work in all that area? I think it should but one never knows.
Also is all that working for mobiles and html5?

I know i will experiment soon with it, but knowing before could save me some time and disappointment.

So will it be:

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Or other way?