There are currently no plans, nor budget, for running the Shinkansen to Sapporo.
It periodically gets approved, then shelved, this moment being one of the later. Current plans are to terminate at Aomori city. The cost of expanding the Seikin tunnel - the longest in the world - to accomodate the bigger trains would be horrendous. Besides, this is one of the few trips in Japan where flying would be genuinely faster than the train so why bother ?
" Help, help ... I'm being oppressed ... "