Someday/maybes don't belong in an Autofocus
Someday/maybe items don't fit well in an Autofocus system. The system's meant for things you have decided to do. Putting someday/maybes in the system clogs it such that I don't want to use it.
Mark Forster's writeup about Autofocus says:
The system consists of one long list of everything that you have to do, written in a ruled notebook (25-35 lines to a page ideal).
Emphasis mine. In particular, it is for things you "have to" do. It isn't meant for "would be cool maybe someday" ideas. This makes it more similar to GTD's next action lists than GTD's someday/maybe lists.
Someday/maybes clog the system because of step/rule 7:
If you go to a page and no item stands out for you on your first pass through it, then all the outstanding items on that page are dismissed without re-entering them. (N.B. This does not apply to the final page, on which you are still writing items). Use a highlighter to mark dismissed items.
If your page is clogged with someday/maybes, you may reach the end without deciding to do any of the items. Following the system as written means you've then got to dismiss all those someday/maybes and not re-enter them. But you don't want to do that, so you either stop using the system (which is what I did) or you break the rule about dismissing all items on the page. But if you aren't going to follow that rule, what you're doing isn't Autofocus anymore, it's a TODO-list.
And, someday/maybes also don't work as TODO list items. Inasmuch as you feel guilty for not getting to an item or items on the list, you will feel guilty about your "backlog." This is pointless guilt because the list isn't actually a backlog. Instead, it's a list of cool options you might want to take someday. It's a reminder. It's not a list of things you have decided to do. A reading list or TV/film watch list or musician list should definitely not feel like a list of obligations. So, such someday/maybe lists do not work as TODO lists.
This is why I would recommend against putting someday/maybe items in an Autofocus.