The ornamental design for a displaysystem for seatback mounting, as shown and described.
FIG. 1 is a front perspective view of an embodiment of the display system for seatback mounting embodying the new design, shown mounted in a seatback for illustrative purposes only;
FIG. 2 is a front perspective view of the embodiment of the display system for seatback mounting, shown separate from the seatback;
FIG. 3 is a front elevational view of the embodiment;
FIG. 4 is a rear elevational view of the embodiment;
FIG. 5 is a left side elevational view of the embodiment;
FIG. 6 is a right side elevational view of the embodiment;
FIG. 7 is a top plan view of the embodiment; and,
FIG. 8 is a bottom plan view of the embodiment.
Features drawn in broken lines are shown for illustrative purposes only, and form no part of the claimed design.