Yes and No.
Referring to what Ed said above, I can somehow make a thing like this to work but not in the nearby future.
On current mods, I've around 25 differen tilesets. Including the ones from base game.
Some of them share the same color palettes for the whole tileset sheets. So then its possible to combine. But i dont have them planned to do for now.
Not sure if this was ever possible in Starcraft 1 though. Combining different tilesets like snow + wasteland + space. Maybe its possible but the game may have same issue about color palette files.
It's a good idea, though.
I planned to use this feature from multiple tilesets, thanks to Ed, to make Ramps for example in War2.
This could be possible but Ed said vision would still be an issue since it not works like Starcraft AND... there's no tech to make hits fail like in Starcraft where like 30-40% of shots miss on high ground