Every time the subject of Led Zeppelin's fifth or sixth "reunion" comes up, Robert Plant says that he doesn't want to do it. Then, you hear some complaints from Jimmy Page. I'm sure that John Paul Jones has something to say and someone probably writes it down. Oh well.
The band reformed and played an awful set in 1985 at Live Aid. Plant and Page got together in the 1990s and recorded an album and went on a tour. Led Zeppelin reformed to play Ahmet Ertegun's tribute concert in 2007. They got together and played live at the O2 Arena. I'm sure there were other "reunions" and whatnot but that's what I can remember.
At some point, you have to conclude that they have reformed and played live and done their bit. They may be leaving a billion dollars on the table, but they are in a position to do so because Plant, at least, doesn't care what's on the table anymore. He knows that every time he says something, someone will go crazy.
In other words, Robert Plant is trolling everyone, and having a laugh at the expense of people who weren't there for the previous reunions. He may have it in the back of his mind to clear 2017 and play 20 shows. Who knows?
It's done. If it happens, it happens. So what?