He will definitely make D League. Wouldn't surprise me one bit if he eventually makes a NBA roster, as a reserve, after a few more years of learning how to play.
He should go overseas. Money is better in Europe and he has little chance of making an NBA roster for a sustained period.
Made sense for Garrett Temple to play in the D-League because he knew he'd get a call-up. The D-League is for guys on the cusp of the NBA needing to stay stateside to be more "available" and guys who just can't stand living in another country.
You can't make a living in the D-League. You can get set up a nice nest egg for the rest of your life if you play 4-5 years in Europe making tax-free money, living on the team's dime (meaning you get to save your cash) and drawing a solidly six-figure income.