If Marvel didn't ignore everything Bunn did, that would have been seen in the books already. We know that Beak became a mutant again and Elixir couldn't cure people who carried the X-Gene from birth, so it's safe to assume he's still like that and others should have gone through the same.
It's also safe to assume, however, that whenever a writer brings back a depowered mutant, they'll repower them through their own plot.