According to Colin Espiner in The Press, Don Brash wants to lead National in the next election. I think the only response to this is "bring it on!" By 2008, Brash will be looking old and tired; his reputation as an honest non-politician (already looking fairly damaged by his conduct ">before and during the election) will be tarred by another three years in Parliament; his appeal to social liberals will likewise be undermined by another three years of sucking up to social conservatives in an effort to get the bigot vote; and most importantly, there will have been another three years of demographic change in ways which will not favour his frankly backward positions on women and Maori.
And OTOH, Helen won't be looking that good either. But I think she could still beat Brash. It's people like John Key and a revived Bill English she should be afraid of, not Don.