**SNIP** After all, a Senate seat is a plum job anywhere, but especially for Democrats in California, where it’s been decades since any of them lost a reelection bid for statewide office. Whoever takes Boxer’s place can expect to become the state’s senior senator after 2018, when the then-85-year-old Dianne Feinstein is also widely expected to retire. But ambitious Democrats should beware: Their eagerness, even greed, could do in their party’s hold on Boxer’s spot. It has happened before in California, and very recently. The field of potential Democratic candidates for Boxer’s slot is large, possibly going beyond obvious prospects...