Luke, Han and Leia would have been side characters or have cameo roles much like the sequel trilogy films had the books continued.
Lucasfilm would not let the characters be killed so i assume they died of old age or something, between crucible and the legacy comics series.
Luke was never going to be the main hero again. Jaina Solo was the new main character, in the cancelled Sword of the Jedi series, supporting characters would have been Jag Fel, Ben Skywalker and Allana Solo.
The new Books would have just filled in the blanks of the era between Crucible and the comics.
NJO was not exactly golden but LOTF was rubbish and FOTJ was worse.
Legacy of the Force was a bad retread of Hayden Skywalker from the prequels with Jacen Solo assuming the role.
“Always loved Vader’s wordless self sacrifice. Another shitty, clueless, revision like Greedo and young Anakin’s ghost. What a fucking shame.” -Simon Pegg.