I'm thinking a prize pool of 20,000 (80 stacks) of zkeys split 1-6 ways (however many original players of a team manage to make it to 25 consecutive victories).
Now even if there is a good turnout (I'm doubting anybody will even read this), 25 consecs might not be achieved, I've done it back in the day but not everyone's that lucky/has that much time. In that case it'll just come down to whoever gets the highest.
If this makes DA as active as it was before the launch of GW2, it will be zkeys well spent. Post in this thread with interest so I can gauge if this has any chance of happening, we have 18~ days until it opens.
Half of the zkeys on one of my 2 storage characters:

Update: The contest is a go. DA will open on the 31st (Or perhaps a day later, I remember that happening with one of the events), there's no official entry to the contest, just play and be sure to take screenshots of your consecutive victories once you feel you're close enough.
Update 2: Given statistics over the past few days, 100 consecs is impossible. Reduced to 25, I feel this will be possible and yet still extremely difficult in the current state of DA.
TELL YOUR FRIENDS! For there to be any hope of achieving a high win streak, there will need to be a decent amount of players, so tell everyone you can, hell, spam it in outposts! Let's make this a fun week.