What does this have to do with the price of tea in China?Rosetta was always going to be a temporary bridge as Apple was paying licensing fees to Transitive, the company who developed that technology. That's on top of Apple's own development costs.
This got worse, or at least didn't change, when IBM bought Transitive in 2008.
I know this because the head of design at Transitive was my lecturer at Uni.
Fitting in those licensing costs into the $29 cost of Lion just wouldn't work, nothing to do with outdated technology. Nice try at scaremongering though.
Supporting everything has a cost. Having that radio button in System Preferences, and the underlying architecture to allow or deny unsigned applications adds complexity, which has a cost in development and maintenance and testing time. Continuing to develop two distinct execution models for signed and unsigned applications over time will require more resources than simply mandating signed code.
You are correct that Rosetta (and Classic before it) was a bridge technology. Likewise, the Gatekeeper preference is a bridge technology.
I expect that the global "Anywhere" option will disappear in 10.9, with the only remaining option being the ability to right-click and allow individual unsigned applications.
If there is a version of OS X (OS 11? OS XI, whatever) after 10.9, I expect that right-click option will disappear then.
That is how Apple transitions work.