I say keep the cards until after the draft. You just never know. Remember some of these guys might not even get drafted like in previous years, so there's a chance Hawks could select one late in the draft. If not a popular club like Richmond or Collingwood could snag one of the guys you have then they could be good trade bait.
I'm in the same boat as you. Am just going to hold onto them until after the draft, if none go to the Hawks i'll try and trade for a Jono O'Rourke sig from 2012.