First, we have a look under the slipcover.
Underneath the slipcover we get... the same art on an insert with a normal Blu-ray case.
The insert details also suggest that once the run with the slipcovers are done, there will be no more digital copies.
If you want a digital copy you'll probably want to pre-order it just in case.
And even though we are a few months before release, Amazon is doing one of their pre-order sales (affiliate links.)
Blu-ray, which will be a Blu-ray/DVD combo pack.
DVD, which will be a stand alone DVD.
The Blu-ray is currently under $16 and the DVD is currently under $10.
Update- In addition, it's currently charting relatively high on the Amazon Blu-ray charts:
On the overall Blu-ray charts it's currently #59.
On the Anime Blu-ray charts it's currently #4.
(As of 2/22 at 1:30pm)
We're still currently awaiting official details from Shout on the release.
The thread with prior information and discussion about tri. part 1 on Blu-ray in the USA can be found here.