Very interesting. One of the reasons why aerial approaches have traditionally been preferred to ground ones has been the ability to move freely in the air, and to adjust your spacing in order to ensure your attacks are safe on shield. Being able to attack on the ground while sliding makes it easier to avoid punishment on block, and a basic turnaround cancel will be useful as a spacing tool, especially against the running shield approach that's been effective in the Invitational and SDCC tournaments. Diddy Kong and other item spawners will use these pivots as the new Glide Tossing, hopefully keeping strategic item usage as an element from Brawl. Unfortunately, it seems to be restricted to either running back and performing a pivot cancel to attack while sliding backward, or running up and performing a double pivot to attack while sliding forward. It seems highly useful as a defensive/zoning tool, a way to follow up certain kinds of combos, and a way to utilize items in a manner similar to Glide Tossing, but it seems kind of limited as a tool for approaching. The one lingering concern I have about Smash 4 is whether there will be adequate shield-safe approach options, and I don't think this will solve this issue, even though it seems to hold a lot of potential in terms of adding to the game in other ways.