Intel's timing was kind of bad with Netburst. They stopped it at 65nm, while the next shrink had much lower power use, and that what was holding back the clock speeds.
Netburst on 45nm would have had extremely high clock speeds. This Celeron would have gone way past 10 GHz. I've always wondered what the stock speeds would be on 45nm, but I would think 6 GHz would have been very easy consider how much more power efficient 45nm was.