If Adobe gave 50% for exclusive images then they could put the hurt on the rest of the agencies. The rest of the agencies would have to come along or fail as the contributors took material away to Adobe. Perhaps Adobe has the current bankroll to do this where the competition is likely not able. It could be a coup to corner the microstock market.

And then we'd have to hope they wouldn't drop the rates when they had cornered the market, which seems to be the habit of successive contributor favourites. Of course, they could win-win by raising prices slowly, slowly; but then others might come in to undercut, as always.