In San Francisco, 810 KGO has expanded its All-News hours but still runs Talk 9am-2pm, 10pm-4am and all weekend. So it's not really an All-News station.
The newest All-News station till Merlin entered the picture was 1000 KOMO Seattle. In a matter of months, KOMO became one of Seattle's most listened to radio stations. But KOMO had advantages, having been a Talk station with a large news department it shares with one of Seattle's top TV stations, KOMO-TV 4. And it was the flagship station of the Mariners baseball team.
Personally, I would've counted KGO as a new "All-News" station, despite the continued talk shows. Along those lines, there's also the recently reformatted WPTF in Raleigh/Durham.
Also, I wouldn't count KOMO as the last "All-News" launch prior to Merlin: Even though it apparently has retrenched recently--and is now pretty much an ARNN outlet--Fort Myers/Naples' WINK did try a largely local format (during the day, at least) that may have included significant partnerships with a couple of newspapers (plus, of course, its TV counterpart).
Here's an article about the format's launch in 2010 (via Wikipedia): http://www.naplesnews.com/news/2010/jul/14/wink-will-launch-am-news-radio-station-1200-1460