Thanks for the helpful replies.
I think I found something that could help:
For open paths you can:
1) Cut at the corners, remove the former end segments,
2) Object>Blend>Make, Object>Blend>Expand, delete the paths on either side of the centre path, which (more or less) coincides with your original path.
"For closed paths you can:
1) Delete the inner path inside the compound path that corresponds to the former stroke.
2) Object>Compound Path>Release,
3) Object>Blend>Make, Object>Blend>Expand, delete the paths on either side (outer and inner) of the centre path, which (more or less) coincides with your original path."
If anyone has an easier suggestion, you'll be more than welcome. Thanks.