In either case erosion would erode the surrounding land and leave the old channel as a raised ridge because the ridge will be more resistant to erosion. An image below, taken with HiRISE of Antoniadi Crater shows sinuous ridges that are old channels that have become inverted.
The outcome of erosion in either situation is the wearing away of surrounding land, leaving behind a raised bank of land that was once a channel, since the ridge is more resistant to erosion. A picture taken by HiRISE illustrates sinuous ridges that were old channels but have been turned upside down.