They don’t need the money. Plant obviously is not interested. I recall Roger Waters who really burned the bridges with the rest of Pink Floyd realized he wanted to bring the band back at the Live 8 Reunion.
Gilmour was not interested, Mason probably not and sadly Rick Wright died about a year later. Gilmour had said in one interview that Waters mentally beat on Wright and Mason so much that he destroyed their confidence. They needed a back up drummer and keyboard player early in their tour when they relaunched post-Waters.
Being in one of these bands usually becomes just a business arrangement. A lot of people cannot stand being around the others after a while in some cases.
I was thinking more along the lines as a last time for the fans thing. Not a lot of traveling for them, spread out the dates to keep down the wear and tear. Let the fans come to them kind of thing.