It's fantasy, but I've always assumed that her next album after Back to Black wouldn't have been half as good - it always struck me as one of those albums where everything clicked into place at the right time.
I suspect that nothing much would have changed if Amy Winehouse had survived. The initial wave of artists that the record companies pushed as Amy Winehouse replacements, most obviously Duffy, either collapsed or branched off in their own direction and Adele has always struck me as the kind of person who is strong on the inside.
This thread has prompted me to rediscover the music of Gabriella Cilmi, which is just as awful as I remember. I suppose the question is, does Amy Winehouse merely survive, or does she turn her life around? In the former case probably the best solution would be for her to leave the music business entirely and live out her life in peace. That would probably require the absence of her dad.