WI: Terrorist attack during Bush's 2001 State of the Union?

What if a terrorist, using a low-yield nuclear device or above extremely powerful bomb, attacked the Capitol during Bush's 2001 SotU, killing everyone inside. The designated survivor was Secretary of Veteran's Affairs, Anthony Principi. He seems like a boring, average kind of guy. Funnily enough, he is similar to Tom Kirkman in this aspect. What would happen next?

Important Deaths
President George W. Bush
Vice President Dick Cheney
Colin Powell
Donald Rumsfeld
Sen. John McCain
Sen. Joe Biden
Sen. Tom Daschle (Minority Leader)
Sen. Trent Lott (Majority Leader)
Sen. Don Nickles (Majority Whip)
Sen. Harry Reid (Minority Whip)
Sen. Chuck Schumer
Sen. Ted Kennedy
Rep. Dennis Hastert (Speaker)
Rep. Tom DeLay (Majority Whip)
Rep. Dick Gephardt (Minority Leader)
Rep. Nancy Pelosi
Rep. Paul Ryan

And countless others
Principi led an Emergency Administration from a secret location while US and World fall in total chaos. James Logan Jones Jr is nominated as Vice-President and confirmed in 2002 then Principi resigns because considered unfit for the role. Jones led US in Great War against Terrorism invading Afghanistan, Iraq, Sudan, Lybia, Iran and Syria. North Korea is spared due Chinese opposition. In 2004 Jones refuses to commit himself to politics and retires. Wesley Clark wins the election for Democrats and then is reelected but greater war fatigue, problems with Arab Spring and a new economic recession led to a republican victory in 2012. Due the nuclear attack, Islamophobia gets an earlier support among right-wing Republicans and Huckabee or Santorum are the new President. And then Warren 2016?