*dusts off tin foil hat*
Gabriel and the Icarus went down, sure, but Gabriel survived and either killed any pirates who got too curious about the Icarus for their own good or scoured the desert to search through the remains of the pirate ships that he personally littered the ground. Once he had gathered enough working parts he rebuilds what he can of the Icarus with mere scrap and a wrench as he was said to often have done and spends the rest of his life co-opting every brigand and mercenary he can into his guild of treasure hunters to further search through the Burrens for pre war technologies. Technologies that have been carefully distributed between the 6 rising factions in the decades after his initial flight so that his shadow guild could control the progress of the new age of airships and play the various sides of the conflict of course compromising certain moralities he may have once had and calling his legacy into question. The Icarus has since been improved upon and possess boss ship abilities that make it impossible to destroy. You can only merely survive it. (Like the Stalker from warframe.) But who mans the helm of the fabled and feared Icarus? an aged Gabriel with a great big bushy beard or perhaps a son (ohhhh or a daughter; what a twist)
tl:dr Gabey lives and went crazy building a rouge nation of advanced badass ships and is a secret boss/side quest story line dealy
I will push this theory super hard.