Whilst I am indifferent on Kirk being killed off in Generations (although perhaps not the way it was handled), it's a shame, retrospectively, that it happened, given Shatner's vitality and longevity in his advanced years.
True, the TOS film years had come to an end, and equally true, even now, there could be an explanation for Shatner's Kirk appearing now, given the limitless abilities of Sci fi.
However, Shatner himself said he would only appear purposefully, with a good script, and not a cameo. Killing him off, really negates any chance of this, or a Picard-esque show or mini series etc.
So whilst I think it would be great to see Shatner don the uniform again - despite being killed off - the act of killing him off drew limitations for him to return. And given his age now, I doubt Shatner will ever return to the role.
Despite all this, he is incredible for his age!