Sure, yeah. A real "cassette adapter" for floppies would need not just a regular one-head magnetic transducer inside the diskette, but some mechanism to determine which track the read-head is trying to read. Maybe another, much more sensitive magnetic transducer, to determine how far away the read-head is from it. Maybe a strain gauge, if the read-head actually makes contact with the medium. Or maybe just a bunch of metallic pads that close different voltages on an ADC ladder circuit — presuming that doesn't disturb the flux pattern being read out by the head.
Though I suppose you don't really need to know where the head is. You could just have an array of very small magnetic transducers, with good magnetic isolation between each one, where each one is looping over a different track; and whatever track the read-head angles onto, it just ends up "plugged into" one of the transducers that was already there waiting for it. Kind of like how a "cassette adapter" for 8-track players would have to work, if one of those was ever made.
Bonus thought: try to imagine how a "cassette adapter" for VHS would have to work. Tape with conductive wire run through it in on a matching slanted raster, etc. There's a reason they never made them :)