IMHO; By definition, the signs are defined as 30-degree segments of the ecliptic, of which there are twelve. To say that a "shift in the earth's axis" adds a "new", 13th sign, implies that this shift either [a]adds to the number of degrees in a circle (360+30=390) or [b] makes the segments 27.6923077-degrees.
Since [a] is impossible and [b] breaks the definition of the zodiac...I think we are all safe in continuing to ignore the "13th" sign, Ophiuchus (or Serpentarius), it's not new and has been around since ancient times, but is rarely used in most cultures. The source of this recent story seems to be an opinion expresses in a comment made to a Minnesota TV crew by a single Minneapolis community college 110 level astronomy teacher named Parke Kunkle.
Scorpio I remain!
