45 was an assumption. It's just that even if there will be layers of increase until their projects releases, it won't be to a point of doubling the framerate from what i know at the moment.
Don't forget the context, and the more important point, this fluidity was witnessed while another view of the main screen was rendered on the padlet, a pretty demanding thing resource-wise. Use the DRC for a 2D inventory/map/virtual buttons, and studios will be able to tap into a non-negligible additional pool of capabilities, with positive results on the main screen (+fps, +IQ, we can even imagine +more intricate scenes with a dynamic engine).
For these titles, you'll basically have a 1x Xbox360 on your TV + a 0,3/0,4/0,5/0,6x Xbox 360 on your hands (480p "current gen" content in terms of complexity + the fact that calculating a different angle of what is displayed on the TV is though as some techies explained in thread 3) + 0,3/0,4/0,5/0,6x Xbox 360 thanks to final graphical polish, additions of effects in the end of development, better image quality, better framerate, thanks to new dev kits, sdk, further hardware and software optimizations, better handling of the asymmetrical hardware setup, improvement on the method to "dual render", etc.
And all this for third-parties ports or titles using inhouse engines already seen before, so expect more from first-parties.
It will be a noticeable leap in the hands of competent & serious & at least a tad ambitious and not-lazy developers.