Probably not quite, because the order in which you carve seams matters for every variant that I'm aware of (forward of backward energy seam carving). That is, if you reduce a 200x200 image to 100x100, you get a different result if you do that in order 200x200 -> 100x200 -> 100x100 than if you do that in order 200x200 -> 200x100 -> 100x100.
But if you constrain it so that any reduced resolution is carved by stepping through the path that represents a straight line from the original image, and pre-generate all images, you might end up with something that looks smooth.
That's more or less what I was trying to convey: for any size reduction, take the route that follows the path with the shortest Euclidian distance[1] (as opposed to Manhattan distance[1]) from the original resolution.
If you do that, then the transitions should look quite smooth. You better memoize the intermediate results if you want decent performance though ;)
So yes, I think your line of thought is on the right track!
But if you constrain it so that any reduced resolution is carved by stepping through the path that represents a straight line from the original image, and pre-generate all images, you might end up with something that looks smooth.