Assuming electrical resistance is only a result of heat inside a wire.
If we take a thin copper wire acting as a fuse between two higher gauge wires, and we wrap it with a non-conductive material to act as a heat sink.
Now that the heat is properly dissipated through the heat sink Would the thin wire lose a lot of it resistivity and can now drive higher currents without breaking ?
"Would the thin wire lose a lot of it resistivity"
Yes, as the wire would have lower temperature and, therefore, lower resistivity.
Let me note that a more efficient way of cooling is by subcooled liquid jet falling on the wire and boiling due to the heat removed from the wire. However, even in this case there is a theoretical limit for the heat removed from the wire (see W. R. Gambill1 and J. H. Lienhard, Journal of Heat Transfer, August 1989, Vol. 111/815)
Yes it would work as you expect.
There is one problem though: most good thermal conductors are also good electrical conductors. Copper is among the better thermal conductors. Have a look at this chart; you'll see nearly that all thermal conductors are metals. Diamond is an exception - it's the best thermal conductor. I would love to see a diamond-insulated wire.
