Anyone can file for or is entitled to appeal. But the better question is will the court agree to hear Bungie's (or Worlds') appeal? Bungie can probably ask for an en banc hearing, or appeal directly to the SCOTUS, and it is very highly unlikely that this current PTAB dispute will be heard en banc or by the SCOTUS.
SO yes the Judges decision is pretty final, just not 100%. Part of my thinking about a remand is because of that and these Judges histories and decisions. WIth Prost being on the panel, I am thinking an en banc hearing would also be highly unlikely. The decision is taking time because they want to get it right, and rock solid whichever way it goes. It is an important precedent setting case. The vacate arguments are good. We shall see which way it goes, but mixed bag is what I anticipate.