Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
Well if it's the only remaining channel link, the port-channel goes down. If not the only remaining channel link, the port-channel continues without it. As you note, you lose bandwidth and I believe traffic will be rehashed across the remaining channel links, which can result in less optimal load distribution.
Protocols like STP or a routing protocol shouldn't see a link outage or flap.