As everyone else seems to be saying, it'd depend on said changes.
But my gut instinct says no.
If the story was given "major changes", it'd no longer be completely mine- but would remain linked to my name. Depending on the nature of those changes, they might dilute or even actively contradict my work's message.
I've always viewed storytelling as a way not only to entertain, but to communicate to the world and say things that matter to me. Due to that, I can't think of anything that'd be more upsetting as a creator than for someone to try to capitalize on my hard work and my story's success and twist the final product in order to send a message I disagree with.
..All that said, I'm also one of those few people who preferred by far the original Fullmetal Alchemist show to the Brotherhood remake which stayed faithful to the source material. I guess if I were going to hand my baby off to someone to do whatever they wanted with it, I'd just want it to be a team I knew respected my work and cared about doing it justice.
Can't deny it would be pretty cool to see my characters animated tho ^^