From a technical perspective, yes. You are basically talking about the Nokia N800 but with a cellphone modem and a bit of effort spent shrinking the bezels down.
But from a product design perspective, I suspect it was impossible to make that leap. We are talking about the point when cellphones were at their very smallest. The 1st gen iphone with it's 3.5" display was considered to be large for a phone. Nobody thought mainstream users would be happy pocketing a phone with a "massive" 4.13" display.
And Nokia were only happy excluding the keyboard from the N800 because it was considered to be a content consumption device. At that time, smartphones were regarded as productivity devices (for email) and the physical keyboard was essential, which would have bulked out the device (See N810).
I don't think we could have gotten to today's large smartphones without first creating a viable browsing experience on an iphone sized display.