The biggest problem with alternatives to floppy drives is that they need to be universal. You've got to be able to count on being able to carry a disk to any other computer and still be able to read it. The floppy disk is the closest we have to that with the CD/RW drives being the next closest. The LS120, ZIP and other alternative drives that were developed worked but were unable to unseat the floppy drive initially and by the time things grew too large for distribution on floppies the CD drives had taken over.
The next best bet for replacing the floppy are the USB connect drives. You can get them from full size, full speed hard drives down to the Flash memory "thumb" drives. For people who need to "sneakernet" things from one place to another those may be their best bet since USB is also close to being universal these days.