I claim the ornamental design for an interchangeable joystick, as shown and described.
FIG. 1 is a top perspective view of an interchangeable joystick, showing my new design;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a left-side elevational view thereof, the right-side elevational view being a mirror image thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a top plan view thereof.
The broken lines seen in FIGS. 2 and 6 immediately adjacent the structure line represent the bounds of the claimed design and forms no part of the claimed design.