Technologies like AJAX at the presentation level and iSCSI at the transport level are so undermining the Fallacies of Distributed Computing that inter and intra-computer communications not carried over IP are looking like special case optimizations. As noted by Cisco's Giancarlo, IP networking is rivaling computer backplane speeds leading him to observe that "It’s time to move the backplane on to the network and redesign the computer".
The HTC is a redesign of the computer. The transition from computers being connected by networks to the network as a computer has been anticipated for some time. The HTC is a model of a computer built from the ground up containing no implicit information about locality or technology.
Computers with just enough processing power to run an instance of a user agent can access the same applications as those with additional processing power and storage available. Locally available processing capacity and storage is presented in the same way as remote processing and storage — that is - as the ability to fulfill HTTP requests. However, unplugging the local computing resources, does not impact the user's or the programmer's view in any way. In this case, other issues such as intellectual property will dominate decisions as to where and how processing is done.