Recess appointments, if not confirmed, are in effect to the end of the next session, not until the recess is over from what I understand. So that would be until the 2018 elections which if Democrats think they could somehow magically get Dems to vote during a midterm election and take the senate back then they could confirm the recess appointment.
People don't like it because it's 'contentious' but saying that if Clinton had one they'd block any appointment for the next 4 years is contentious as well.
I think this was the article I'd posted back then that mentioned it
http://www.thedailybeast.com/article...al-crisis.html