Well, here's the thing. There really isn't much they can do with it.

Option 1: Stock it full of stuff that's already on the market.
This would be bad because it'd be just another currency to juggle around when making fits and I know sure as hell that if the DK market is just a copy/paste of the already existing market I'm going to be very disappointed, personally. I already have issues with restocking when it comes to LP and Aurum items hybridized with ISK stuff.

That's totally the issue with this but if it's to totally restock your PC fits then I wouldn't mind it

Option 2: Stock it with unique stuff that is powerful (like 'officer' modules or something)
This would be bad because it'd create a positive feedback loop. Players would play PC, get DK, spend that DK on progressively better items.... with which to play (and win) more PC, and get more DK. It'd effectively make entities already in PC extremely powerful and they'd be able to keep their power because of the difficulty involved in players combating them for a foothold in PC.

While this would be quite risky because it would make the gap between enstabilished corps and upcoming corps even further, on the other hand it would boost PC competition and grinding, that is if these modules wouldn't be extremely powerful but just give a percentage of advantage to proto modules

Option 3: Cosmetic options and otherwise non-gameplay changing stuff
Exclusive SKINs and the like. I know a lot of PC players would be very disappointed with this because they want that in-game advantage but honestly it's probably the only way that CCP can go about it without causing issues with Option 1 or 2.

It certainly is the safest but something actually useful is required.

That's my thinking, anyway. But the 'refresh' option on the market UI for the DK Market is intriguing, to say the least. I'm wondering how useful that mechanic will be, if it is useful at all.

To cost only 20 DK I don't think it'll be much useful but it'd already be something

Honestly I wouldn't mind seeing something akin to Eve Online's Boosters. Temporary bonuses to different things (damage, rate of fire, magazine count, etc) that are very very expensive and something that you'd want to hold onto for a rainy day. Like, if you know you're going to fight that corp that is extremely hard to win against and you need just -a little extra performance- out of the deal. Just a spitballed idea though.
That's a cool idea but it would make for other 'balance' agony and stuff if it applies to pubs