Hokkaido Shinkansen was opened in March 26, 2016. You can get Hokkaido by Shinkansen directly without changing trains at Shin-Aomori.
I have received some questions about train transfer at Shin-Aomori station. Shin-Aomori is the last station of Tohoku Shinkansen from Tokyo. And this station is the place to change the train to Hokkaido, like Hakodate and Sapporo. Some travellers worry about the transfer. They are not sure how big Shin-Aomori station and how many minutes is a enough to transfer the trains.
Super Hakucho and Hakucho is no longer running after Hokkaido Shinkansen opened in March, 2016. Now Hokkaido Shinkansen connects Tokyo and Hokkaido directly. Please see the following link to see the details of this Shinkansen line.
Hakucho/Super Hakucho is operated between Shin-Aomori (新青森) and Hakodate (函館). These trains go through the longest tunnel in Japan, “Seikan Tunnel” and connect the main island in Japan, “Honshu” (本州) and Hokkaido (北海道). All these trains are scheduled to be connected with Tohoku Shinkansen at Shin- Aomori station and Limited Express “Hokuto” and “Super Hokuto” to Sapporo at Hakodate. These trains used to connect Hachinohe with Hakodate via Aomori. But Tohoku Shinkansen was extended to Shin-Aomori on December 4, 2010. Departure location had been changed to Shin-Aomori instead of Hachinohe.