In all honesty, any major changes to Pantheon that would cause an animation change would come along with the VU he desperately needs and possibly a slight rework in his abilities. Like a gangplank level rework.
But that's not coming for a while (from what I can tell, not really my personal opinion) since Pantheon is in a fine place at the moment and his kit is still relevant (Oh noes, it's point and click!) despite his age.
If they ever turned his Q from a point and click to a skill shot, then they'd probably have to change where his power spike is.