Does it really matter?

The big question about Sarah Palin is does it really matter who is the Vice President of the USA. Of course it does, as the memory of Lyndon Johnson will remind us, because when if the President dies then the VP becomes the President. And, however well you think she might or might not perform she would also be the Commander in Chief, and the one who would push any nuclear weapon button.
One of the great strengths about the American system is that it allows for a 'character' to be in the fairly innocuous post of VP, without too much of a worry that it will actually effect good government. Which is fine as long the VP doesn't become the Prez
What I think is interesting is that despite the fact that she was no doubt brought in to add a sense of the modern to the McCain campaign, to be seen as both young, energetic and (of course) a woman; she also exposes the one thing about McCain that the electorate is nervous about, and that is that he is an old man.
The talk about Palin is not... why shouldn't we have such a different VP?.... but what happen if the old man dies. Polling has it that up to one third of the electorate is troubled by this.
Now, I think that old people should not be discounted just because they are old ( I am fast becoming onesuch myself) but my work every day informs me that after 70 two things can happen.
One is that mature people can function really well, and can bring a tempered stability, wisdom and insight which is often lacking in the 30 and 40 year olds. But I also know that it is a mistake to assume that age brings wisdom automatically, I can think of at least two cases where 'elders' in our own community just became more and more idiotic.
The Second factor is, that despite our desire to the contrary, there is nevertheless an inevitability that the chance of people undergoing rapid decline in, say, any given six month period is obviously much greater. That is, we can be fine one month and by Christmas be out of it. We can go on for years and then suddenly undergo a decline whioch may at first be denied, or take a litttle while to pin down...may the world be protected from a declining leader who has the authority to crash the world economy, invade countries or blow the whole show up.