The solution? When there are insufficient stitches to complete the full cable, work the remaining stitches in something resembling the original cable as much as possible.
Example #1: my sweater has columns of OXO cables worked over 8 stitches. When there were not enough stitches left to "place 2 stitches onto a cable needle, hold them at the back, k2, then k2 from the cable needle", I placed 1 stitch onto the cable needle, held it at the back, then knitted 2, then knitted the 1 stitch from the cable needle. OK, I didn't actually use a cable needle (see here for cabling without one), but you get the idea.
Example #2: when the same OXO cable lost more stitches from the other side due to some neck decreasing, leaving only 6 stitches for the entire cable, I brought only 1 stitch from each side to the centre to close the "O" while still moving the original 4 centre stitches to the back.
What does the result look like?
In the above pic you can just catch the beginning of the neck shaping in the upper left corner along with the raglan shaping that's in progress on the right hand side. As the OXO cable is squeezed from both sides, some alteration in the manipulation of the cable was needed to keep it going as long as possible.
The result is an OXO cable that doesn't quite look like the original, but comes close enough to fool the eye into seeing an undisturbed column of cables. Much better than a big patch of stocking stitch in a sea of cables.
BTW, manipulating cables while working raglan decreases is relatively simple when you are working in the round, as I am with this sweater. It's easy to keep all the cables doing the same things as you work them all in one round, as opposed to working in pieces and having to check your previous work to see that you've made everything match. Cable on!
