Flip was cancelled just ahead of nearly every smartphone having capability to record comparable quality video. It was a smart move by Cisco.

It seems less likely that phones will be able to supercede GoPro in the same way, since you'd never want to subject such an important device to the physical situations that you would a GoPro.

The lens issue is also non-trivial. For a general purpose camera (i.e. smartphone), you wouldn't want a wide angle lens like you would for PoV video, and making a smartphone's camera lens interchangeable for a small segment of its customers probably isn't happening broadly if ever.

They were popular. Cisco bought them at their height. Shortly after the purchase Cisco saw the cliff.