And if you 'zoom in' with binoculars and stuff you have to solve that too, how trees convert from low to high poly count if you zoom into them from distance
This is very important also in relation to this:
Only update animation for meshes that are not hidden or far away
In Battlefield 1942 (at least, in older versions) the developers forgot to animate characters in the distance when viewed through a sniper scope, so they sort of slide around instead of walking...