Interesting question. The non-grace note version of flams would essentially be a double stroke roll. If you think about the sticking of alternating flams: lR rL lR rL (lower case indicates grace notes), we can see the collapsed double strokes in there.
Flams don't suffer from the same ambiguity of drags though, really. They can be interpreted very closed or very open (pipe drumming plays them as buzz strokes, for example), but there isn't really an equivalent of that discussed in the drags paper.
If you're interested, have a look at some work on collapsed rolls. The Double strokes collapsing to flams is a good example of that.