Everybody in this thread is discussing the two new design paradigms I identified as being increasingly 'trendy' in D&D design and likely to significantly impact the design of the 4th edition and this is fine, as that is one of the purposes of this thread. I also sought, however, to identify other such paradigms that are in increasing use by D&D designers or are in planning stages. Hence, I am adding a third paradigm to the discussion, which, although it has not seen as much use as the other two, appears to be at least in the planning stages. I will update my original starting post, but am also presenting it here:
New Design Paradigm 3: Monsters will be designed in such a way as to eliminate the dissonance between their respective Challenge Ratings and their Hit Dice. If combined with per encounter balancing of monsters... and it will likely be thus combined... this will also eliminate the discrepancy between the usefulness of abilities to monsters and PCs and thus unify Challenge Ratings, Hit Dice, Level Adjustments and Effective Character Levels into one number: Hit Dice
Evidence: My evidence for this is weaker than for the previous two new design guidelines and consists essentially of the articles on monster design published by Mike Mearls several months ago on the WotC website. (As a sidenote, what happened to more of this series of articles? I think I ever only saw two or three.)
My position: I have mixed feelings. On the one hand having hit dice deal with everything four numbers used to cover previously seems like a good idea, as it appears to be more streamlining than the elimination of any important mechanisms. Conversely, however, I feel this may restrict monster design choice/freedom by bundling abilities into hit dice. Personally, I would give this change a tentative heads up, as I suspect that monster design freedom/choice might not be too adversely affected and if done right, it might also simplify the creation of new monsters by DMs. I guess it depends on implementation, but it does sound promising.
Note: Per encounter balancing, although it will surely be used, is not actually necessary to achieve this - it is merely necessary to design monsters in such a way that their abilities equivalent to PC abilities of the same hit dice are not useable more frequently than those of the PCs unless there is some equivalent tradeoff.