Given that 35357 is keystone's IANA assigned port, I don't think it's reasonable to expect keystone to change ports in the short term. In the long term (after dropping API v2 support), keystone will be deployable on any one port. Using 35357 theoretically aids discoverability a tiny bit, but there are other means of discoverability that we can investigate in the future (such as RFC 2782).
Given that 35357 is keystone's IANA assigned port, I don't think it's reasonable to expect keystone to change ports in the short term. In the long term (after dropping API v2 support), keystone will be deployable on any one port. Using 35357 theoretically aids discoverability a tiny bit, but there are other means of discoverability that we can investigate in the future (such as RFC 2782).