DON'T PANIC. As we discussed before, this is a different beast than it was a couple of years back when Semaj declared for the draft. The deadline to withdraw from consideration for the draft has been pushed back, so Trevon's declaring is different than Trevon's leaving.
This basically means that Tre will get to go through the combine and be evaluated by NBA scouts. He will also get to work out for a team and receive feedback from them. After he has gathered that info, he will have the opportunity to make a decision regarding his next steps.