Re: Efficiency savings?
Perhaps there is the technology to wire a load of screens and keyboards together and run one PC as a true multi-user host but it isn't obvious.
The systems I manage at work serve at least half a dozen users, each with 5 to 8 screens. Now, the X display controllers are essentially full-blown Linux PCs themselves, but they're not doing any actual computation except for one particular subtask on a number of them.
Setting things up like that isn't particularly difficult but you're not gaining anything because the cheapest way to get a remote terminal for your central system is by getting a tablet, laptop or even a PC. I think that only if you have a totally 'dumb' terminal with a total energy requirement just a tick over that of the screen will the effort pay off.