According to one of the frequent flyer websites, transfers between Velocity and SQ are about to be switched back on.
"While Rohrlach is hesitant to “commit to the exact date” on transfers taking place once again, he says “we’re definitely working as hard as we can on that because we know it’s really, attractive to out members… I’m pretty confident we'll have some good news soon.”
and
"Also coming back: the ability to use Velocity Points to book first class and premium economy seats on Singapore Airlines’ flights."