Official comment
You can have Step Sequences appear on the Unsubscribe Page by clicking the Settings button and then selecting the checkbox:
In this case, I have a Step Sequence named "Weekly Email Newsletter" that I will show on the unsubscribe page for all Contacts who are subscribed to that sequence. That may be enough for your purposes if you only have a few sequences that send email. In this image I have three Sequences listed on the page.
You can get a lot more creative if you need to; if you have dozens of sequences sending email you might not want to list them all on the unsubscribe page. In that case, create a "proxy" Step Sequence that just has a Rule step tagging the contacts. Add a global Rule in Contacts > Rules that looks for the contact unsubscribing from that sequence and then removes them from the tag (and any sequences that send email weekly).
