Every club has changed their guernsey.Port don't, shouldn't have too, and won't. That's all that matters here.
If a club like Essendon for example wants to bastardise their traditional guernsey every which way with a fat sash, red sash on grey, red sash on red, etc to give the impression and show supporters that they're somehow continuing to be be true to their heritage, then that's up to them.
The Essendon guernsey is black with a red sash.
The Port Adelaide heritage guernsey is black and white prison bars with the white number panel. If I was a Port supporter, the only teal I'd want to see on that guernsey is the teal on the Power logo. And that appears to be the consensus among Port supporters themselves.
Port had no black and white originally.