I find that hard to believe considering they left the door open for Data to return at the end of Nemesis. Kirk and Trip didn't have any hint of coming back from the dead when they were killed off onscreen. They made it far easier to write Data back to life.
Kirk was pretty much dead. But I do think there was a backdoor with Tucker, with respect that we last saw him--stil alive--vanishing into a tube of undisclosed function. Later dialogue strongly suggested Tucker was dead, but it would have been simple enough, had a miracle occured and ENT was picked up for another season, to claim that was a statis tube and Tucker was being put into storage, near death, until a way to help him could be found. Then, presumably, at some point (because TATV was several years into the series' future) we would have had a STIII-style arc to save Tucker before he was too far gone.
...frankly, I'm not sure why that wasn't used in the rush to resurrect Tucker for the books, instead of the tottering house of cards we wound up with. And I'd have much preferred that, if anybody would have gotten the 'Get out of Death' card, it would have been Data rather than Tucker (for the entirely selfish reason that I prefer Data as a character; I do recognize that Data had a better, more heroic death than the silly, slapdash death Tucker got).
Fictitiously yours, Trent Roman