Sadly, very few specifics are now prohibited. High fives with fans, jumping into the stands, planned group actions by players from the previous down (without props), even diving over the goal line (without some sort of taunting action), would all seem to, now, be allowed.
So, yeah, spiking the ball (not toward an opponent), spinning the ball, dunking the ball over the crossbar, etc., etc., would now seem to be allowed, as long as there is no taunting action, or something that takes an extraordinary amount of time, i.e., delays game officials in spotting the ball and getting both teams in place for the next down.
It would be nice if they would issue a bulletin - if not put directly into the rules - such a listing of known actions that are not fouls. Dream on…