Update 7/16/06: More stuff added to the bottom of this, courtesy former editor KC Carlson (via Johanna Draper).
Dipping into my old email archives, here's a compilation of some messages from 1998-2001....
The story of what Keith Giffen was going to do with the Legion when the SW6 Batch came in is pretty far out. You might read this and not believe it, but it's true. Giffen's plan is known in Legion fandom as "The Hat Trick", and it's got nothing to do with hockey.
The name itself started either with the early mailing list [lsh-l] or on usenet's Legion newsgroup, rec.arts.comics.dc.lsh. The earliest reference to the incident was in my 1995 San Diego Con report, posted to the newsgroup Aug. 9, 1995. In San Diego, a bunch of Legion fans got together to hang out. One of those fans was then-editor KC Carlson, who told us some interesting stories. The rest of this post is taken from my con report, Troy McNemar’s con report (not online), a Feb. 1999 AOL chat that Giffen attended, and Jef Peckham’s June 1999 Heroes Con report (not online).
According to KC Carlson, this was around the time when Giffen was debating on whether to stay with the Legion or not. KC was editor at the time.
Giffen described this time period in Legion history as "the one story I wish I could have finished up right."
Stitched together from three different reports:
His plan was this: the SW6ers were the real Legionnaires, and the "adults" were clones created by the Dominators circa Adventure #348-349ish - so for the last 20 years or so, we had been reading the Legion of Cloned Super-Heroes. The adults’ secret programming would kick in and the two teams (kid SW6 and adult LSH) would have a “massive battle” to the death -- with the victims chosen at random, their names literally pulled out of a hat by the writer(s). Then after it was all over, the two teams would make up, then the senior team would then leave United Planets space for the Vega System and call themselves THE OMEGA MEN in their own book.
KC at this point said, basically, "No way, this is not going to happen", and that made up Giffen's mind to leave the series.
Asked a few years later, according to Peckham's Heroes Con report, Giffen corrected this version, saying he wasn’t going to have it where half would die and the rest join as one Legion.
He only planned that "some" would die, considerably less than half, perhaps 5 to 10, in the battle to free Earth from the Dominion. After that, the older Legionnaires were going to be given Earth and the defense of the UP headquarters, while the younger team were going to the edges of UP space and act as the last line of defense, in a new book to be called The Omega Men.
Keith said it was TPTB's insistence on the removal of Mon-El, simply because of the "El" name, was what led the Bierbaums to write the “Mordruverse” issue of V4. He said it was all the Bierbaums doing, and he refused to be associated with that issue over his objections with what was TPTB wanted accomplished.
He claimed that TPTB at DC had been pressuring the creators to pay less attention to continuity and Legion history, and in fact were looking for a reboot years before it actually happened. He also said that this pressure to toss out 30 years of Legion history was what ultimately made him quit the book. As a side note, he said that he destroyed Earth as he left because "no one was watching."
So there you have it. An urban legend that's actually true.
Update: More info from KC and Johanna via email, reposted with permission.
Johanna says: "If you want to add the following from KC, you're welcome to. (This is kicking off from the last paragraph from Giffen.)"
I wasn't aware of any plans to reboot the series before we actually did it in Zero Hour. We (me, Mark Waid, and Tom McCraw) came up with the idea ourselves, and Carlin and Levitz signed off on it. There may have been some tinkering regarding the SW6 characters in getting the Legionnaires book started, but Michael Eury is the person to ask about that, since that series went through several false starts before it came to market.
Keith says that he bumped off Earth because no one was paying attention, and he's right. The book was editorially transitioning again, and the Earth blowing up issue wound up being my first. However, not many people know that TPTB had noticed what Keith was doing, and as soon as I started, they asked that that issue not be published. I had to fight for its publication, because that issue was virtually complete when I walked in the door. It was suggested it be cancelled, but it was so close to publication that trashing it would have thrown the schedule completely off, and I didn't want to start by making the book late.
I also understood that several hoops had to be jumped through to get Neil Gaiman to sign off on the Death cameo, and I didn't want that to go to waste, because I thought it was a good bit. Although I had nothing creatively to do with that issue, I was happy to fight for it, because I thought it was an excellent piece of work.