Content & Quality: the new RPG!
What may eventually happen to RPG books is they'll look like the booklets to wargames.
Instead of getting a beautiful hardcover tome that has beautiful art, you'll get a softcover with some cover art or embossing and page after page of nothing but rules and explanations...and there's nothing at all wrong with that.
I loved Task Force Games' Starfire and StarFleet Battles, and their rulebooks are what I'm thinking about. Almost all of the art in their game books were devoted to explaining game situations, and were black-and-white. Everything was compact and the rules were even given section numbers, so you could easily find something by its code- even if the edition changed or there was a second printing! Supplemental rules were given codes that let you know EXACTLY where a particular rule fit in the system... Supplemental Rule 2.0.4 came before rule 2.1 and after 2.0.3. 5 years later, a supplement comes around with Rule 2.0.4a, and you KNOW what's going on immediately.
Instead of spending $30 on the first fancy rulebook of 3, you got a softcover, maps, and (cardboard) counters for the same money- and that was all you needed. Sure, expansions followed, but they were similarly value-priced.
So, instead of increasingly elaborate and expensive rulebooks, what about a return to the boxed set.
Imagine, the DMG, PHB, and MM#1 as TFG-style softcovers, with a module, gameworld maps, a set of die, and a set of plastic minis (one for each of the archetypal PCs in the PHB- like Krusk, Jozan, Mialee, etc.) all in one $50-65 box. Each of the books would be available seperately for $15, of course, for those among us who need extras. (Wear and tear, accidents, and casual players without their own copies make me buy extra copies- I'm a nice guy.)
With a smaller but more legible typeface unobscured by artistic touches like fake sepia-tone antiquing, the books could even be printed in digest size (4.5"x 6").
Or maybe everything winds up on a CD-ROM in Word or PDF format, and we either use it from the computer or take it to Kinko's to get printed. (BTW: I heartily reccomend spiral binding for that- I use it when I get my sheet-music rebound at Kinkos- it lies flat and holds up.) Maybe the CD-ROM is even part of the Box set.
Heck- they could even keep making the hardcovers with the high production values and thus, the higher costs.
But I bet that box set would sell like mad.