The story of his final days is also Creator Breakdown - albeit one mostly allowed and imposed from the outside. First he joined Shinso's religion for help getting clean/coming to terms with himself and his problems. Unfortunately, Shinso provided very little meaningful mental health help and did introduce him to Kitami Terumi, and pressured Taiji to bring on Kitami as his manager and keep her as such. The trips to Saipan and the draining of what little remaining cash Taiji had from his 2010 gig with X Japan and his other ventures ensued - as did Taiji being told to keep everything away from the people who could have helped him. By the time he had realized what was going on, he was likely using methamphetamine and abusing alcohol again (in his final photos, his arms showed evidence of injection, and there were photos of him drinking alcohol), was in a desperate financial and social situation, and in a horrible enough place mentally to think Violence Is the Only Option - on an airplane, no less - and got into a fight with Kitami on the flight, and things only got much worse from there...
No Budget: Pretty much defined his career (not to mention his life) after 1994 until around 2009-10. A specific example in his works would be D.T.R's PV for Cybernetic Crime, where the video is so horribly shot and of such bad quality even for the mid 1990s that it is one of the worst presentations of the song.
Outlived Its Creator: TSP as a band, which Shu kept ongoing as a memorial and as an act in and of its own right.
What if he had never been introduced to stimulants? Had he never gotten involved with the amphetamine-class drugs (or had but had been able to remain a Functional Addict) he likely would have had a much better life. He likely would never have spent all of his money and royalties from X Japan and Loudness, he wouldn't have had the stroke/the epilepsy it uncovered to be far worse, his career and home life probably would have been far more stable, and even the situation leading to his death probably would have been averted.
What if he'd never gotten kicked out of X Japan or Loudness? Again, he would have had a far more stable career and income, and both bands would have produced even better bodies of work than they already did. If you can imagine Taiji's bassline on, say, Dahlia instead of Heath's, you can just imagine how epic this would have been.
What if on their departure from Loudness he and Munetaka Higuchi had formed their own thrash band, picking up guitarists and a singer? Had he gone this direction rather than the far more experimental (and only much later appreciated) D.T.R., they would have likely been successful even with metal going out of style being heavy drum and bass Thrash Metal.
Much of D.T.R's music wouldn't have been out of place in a Space Western - and since the genre was being made in The Nineties, it's just another odd thing that he and Yoko Kanno, for example, never worked together. (If you want to imagine how Cowboy Bebop's soundtrack could have been even more badass...)
What if he had learned to adapt D.T.R.'s sound a bit more, and/or worked with another band until its style of metal rode the Popularity Polynomial back up in the late 2000s?
What if he *had* gotten valid, legitimate help for his addictions and illnesses and stuck with it at least enough to remain the Functional Addict and not well but alive and surviving?
What if X Japan had let him stay in 2010, either as sole bassist or in becoming a double bass band along with Heath?
What if he had told Toshi about Shinso/Shinsho in early 2011? Probably one of the saddest of these, as Toshi, from his own experience with a Scam Religion, probably would have given him the information that would have saved what was left of his money and his life - that he needed to get away from the guru, lawyer up to break the contracts etcetera, and get real help.
What if he had just gone blank instead of fighting/having an overt seizure on the plane?
What if the arresting officers had noticed his unwell state and had him sent to a place with valid neuropsychiatric care outside of Saipan and banned Kitami or Shinso from any contact with him until the situation had been sorted out?
What if he had at some point before he died gotten a competent lawyer who had immediately bailed him out of jail and gotten him out of Saipan?
What if someone had called BS on Shinso's requisitioning the body and had demanded an autopsy?