Sam hasn't announced yet himself but based off of the interviews from the Capitol Classic I don't think there is any doubt. Both Seth Allen & Damonte Dodd refer to Sam as a future teammate. Damonte hits on it in greater depth. Check it out for yourself.
"Sam he got a mean step back"
I find it very odd that both of these players would be discussing Sam as a teammate unless they knew something that wasn't made public yet. Couple that with the timing of the announcement, I am 99% sure he will be a Terp.
Edit: SCJr has officially re-committed to play for MD. Rounds out 7 man class including the transfer of Smotrycz from Michigan.