It looks like the ATI RV610 will bring DirectX 10 to AGP systems:
We guess that ATI found the way to make it work via RIALTO bridge chip. ATI plans to use the bridge chip on a new PCB and make even more money out of its RV610 bridged architecture. It looks like Nvidia doesn’t want to go this AGP way. At some point in May / June time the market should see the dawn of ATI's DirectX 10 cards, probably named Radeon X2300 xx AGP.This Radeon X2300 AGP is expected to cost about $100-$115. More info at Fudo's new site.