This article is from the X-Men Comic Books FAQ, by Kate the Short (firstname.lastname@example.org) with numerous contributions by others.
Alan Davis, creator of Cerise, Kylun (based on the boy from Excalibur
#1, created by Claremont/Davis), Micromax, and Feron, quit to do other
things. After his departure, Marvel decided they wanted Excalibur to be
more of a mutants-only title, and started systematically getting rid of
Excalibur #58 was the last of the Davis issues, although #56-57 were
actually scripted by Scott Lobdell. The issues after were written by
Scott Lobdell and/or Richard Ashford, and are stories that make
Excalibur fans howl in agony, even before the undignified retirement of
characters fans had come to like.
Cerise left in #70. Cerise had been in the Shi'ar military before her
time in Excalibur, on a recruiting ship. Not approving of the atrocities
the crew committed in the name of the Shi'ar Empire (looting, pillaging,
genocide, etc.), she sent the ship into a sun. She did teleport herself
out first--that's how she landed in Excalibur. Now, Lilandra could not
let this pass. While she did not want her military committing such
crimes and sullying the name of the Empire, neither did she want unhappy
soldiers destroying valuable starships. Her solution was to sentence
Cerise to work for her as an aide, rooting out similar abuses. While a
cushy civil service job is better than a prison planet, this did
preclude Cerise staying on Earth (Excalibur #68-70). She attended Brian
and Meggan's wedding in Excalibur 125, and helped the X-Men during the
Maximum Security Crossover, where she was featured in X-Men #107 and
Maximum Security #3.
At least Cerise got a send-off; the others didn't do quite so well. But
Ben Raab, the last writer on the title (which was cancelled after issue
#125), was kind enough to answer the pleas of fans to get the dangling
plotlines regarding these characters resolved once and for all.
Feron was last seen under a waterfall, pining with Meggan (#71). Meggan
eventually got out, but Feron was forgotten about by the rest of the
team until he resurfaced in #124.
Micromax went to America to pursue a job offer (#71). As of #125, he
was still unemployed.
Kylun went to look for his family (#71), and is still living with them
Rachel was also part of the purge; she replaced Captain Britain in the
timestream in #75. She popped back out of the timestream far in the
future in The Adventures of Cyclops and Phoenix LS #1, and by #4 had
died of natural causes. Of course, an earlier version of her also
appeared in Cable, where her brother rescued her. She decided to go
to college and try to be normal.
Pete Wisdom broke up with Kitty in the early 100s of the title. He left
Excalibur shortly before the team disbanded in Excalibur #125. He acted
as a mission overseer and team trainer during X-Force #102-105. Pete
died in X-Force #105, and his funeral was in issue #106. Of course, he
was faking. He reappeared in X-Force #115.
Brian Braddock and Meggan finally had their wedding in Excalibur #125.
They last appeared in the Excalibur: Sword of Power mini-series. They
also showed up for Betsy's funeral in X-Treme X-Men #3.
Lockheed just disappeared. He wasn't seen again until X-Treme X-Men
Annual 2001, though he also showed up for the Mechanix limited series.
Moira MacTaggert remained on Muir, working with daughter Rahne to find a
cure for the Legacy Virus. She died a few months later, when Mystique
set off a series of explosions on Muir Isle (X-Men #108). In death,
Moira transferred information about the Legacy Virus to Xavier's mind
(she may have suggested to Charles that Mystique's manipulation of the
virus was the key). Beast created a cure with Moira's knowledge.
Piotr, whose guilt over his sister's death from Legacy led him to join
Magneto's Acolytes, joined Excalibur after Avalon was destroyed in X-Men
#43. He beat up Pete Wisdom, but eventually became a full member of the
team. He left Excalibur to rejoin the X-Men. After Moira's death and
Beast's creation of the cure, Piotr took a vial full of the virus and
injected himself with it. Legacy was cured, but Colossus died in the
process (Uncanny #390). His feeling at the time was that it made up for
his failure to save his sister.
Kitty, who had joined Excalibur after recovering from her Mutant
Massacre / Marauders injuries, made her way back to the United States
with Kurt and Piotr, just in time to lose her powers along with the rest
of the X-Men, regain her powers, and fight Apocalypse. Shadowcat then
disappeared during the Neo storyline (and never revealed where she'd
been). She left the team after hearing of Piotr's death. She was last
seen enrolled in college (X-Men #111), and has also appeared in the
X-Treme X-Men Annual 2001 backup story and X-Men Unlimited #36, where
it's clear that she's enrolled in the University of Chicago. She was
in the Mechanix limited series, appeared as a major part of the God
Loves, Man Kills II storyline in X-Treme #24-30, and has since gone
back to school.