Work commitments? That's a good one. Let's be honest, in recent years the Frakester's CV has been thinner than his hair line.
Was expecting this anyway. When you consider that Nimoy has retired, Nana Visitor and Beltran have been to the UK once already this year, and Jolene Blalock doesn't seem to do appearances, DSTL would look very thin without at least one First Officer.
I'll be surprised if Frakes isn't announced. 25th anniversary of TNG this year, and so far all we've got is Patrick. This event is so far being left wanting given the ticket prices. It's not like they can afford to leave the bigger announcements until later on as they need to sell those £900 tickets.