The Republican response — indeed, the opposition-party response — to the State of the Union is usually the graveyard of upward ambitions. Not tonight. Paul Ryan, the Wisconsin congressman, is giving what is certainly the best such response in memory, and will — and should — spark serious talk about him as the Republican nominee next year. He has said flatly he’s not running. Maybe it would be wiser for a 41-year-old like Ryan to wait until 2016. But this speech reminds us that the deep bench of younger politicians — with Ryan and Marco Rubio and Chris Christie and Bobby Jindal and Nikki Haley, among many others — really belongs to the GOP.