A large, established website made the decision to change all urls from HTTP to HTTPS. They did all the right things with 301 redirects and canonicals. But now they want to return to HTTP. So the site would go from HTTP->HTTPS->HTTP in a matter of two weeks.
This sounds like a disaster to me. I don't want to get into why they went to HTTPS and why they want to go back, as its a different discussion. I am interested in reporting the likely effect on google search results to them, and understanding any mitigation if they do proceed.
I would do the analysis to see how many URLs with https are now indexed and how many remained http. Since it seems that there are less than 2 weeks passed since the move to https, Google may still have a fair amount of http pages in its index.
My experience in cases like this is that if they are quickly reverted, and revert is done technically correctly, there is no long term damage, although it may take Google some months to sort it all out.
If change back to http is preferred, then in this case I would:
- Remove the 301 redirect http --> https - Change back the canonical link element to http at the same time - Introduce redirect https to http at the same time - TEST it all works as expected - Go to Google Webmaster Tools, do Fetch as Googlebot of the http home page and submit the page and all linked pages to index
Google is *usually* forgiving in cases like this one, although there are always risks involved.
A gut feel tells me that it would be worse to wait some months for Google to fully index https and then revert back to http, but this is just a gut feel.