Well if they make the upgrade and it does turn the Dreamcast into a Naomi 2 then it will be as good as the other systems.
Basically, the Naomi 2 is just a normal Naomi with additions to its PowerVR 2 chip (T&L and hardware environmental mapping) and a bunch more RAM. It's performance is roughly 10 million polygons a second, which is well more than any PS2 game so far.
And its fully backwards compatible.