Chances are that Cheney will take the blame for shortfalls in policy. Bush may have to choose a different running mate for '04. Powell already said he wasn't coming back for another term. Ari Fleicher and Paul O'Neil already left and I think Carol Browner, head of EPA, left too. Still seems like a relatively strong administration unlike the Reagan administration which was rocked by scandals and saw a lot of heads roll.
If a Democratic candidate makes it to the White House, that person will more than likely have to be right of center. One can already see some influence, for instance, look at Dean's stance on gun rights.
A person can make all kinds of campaign promises to elicit votes. Let's just hope whomever he is that he keeps the important ones for the sake of the majority of the people rather than for special interests.
Oh BTW, do you remember Bush's "I'm a uniter, not a divider" then afterwards, "you're either with us or you're against us." Funny...