I see a third DT as our biggest need and most likely next signing. I don't know anything about Miller so I'm not saying it's him, but it's definitely a positional need.
There are five DT's on the roster behind Suh and Phillips. I am thinking this was a "due diligence" interview and nothing will happen until the team sees those five on the field. However if those guys stumble out of the gate, look for them to sign someone right away. If Miller has recovered from his Achilles injury, he could well be the best of the lot.