Honestly, I don't know.
I could deal with a Player's Handbook with a thousand pages, but I probably wouldn't want to. The Pathfinder RPG Core Rulebook and the 20th Anniversary Edition Vampire: the Masquerade books are 500+ pages each. While I enjoy the fact that they're comprehensive, I don't so much like the fact that they're heavy. I have to actually set those books down on a table to read it, I can't casually flip through them as I'm going to bed, for example.
What I'd like to see is products sold by level ranges. Despite 4E's attempt to widen the "sweet spot," most groups still have a preferred level range, and I'd love to buy something with more material that I'll actually use.
For example, you could make a starter set similar to the Pathfinder RPG Beginner Box covering levels 1-5 or so. Make it a genuine introductory product that has a low price point and the bits and gewgaws that people like to get (tokens, maps, dice and so forth). Make sure that it includes the full version of the rules and the characters play in the full version of the game.
Then make a Heroic Player's Handbook covering only the heroic tier. Make it 320 pages, and pack it full of material for those levels. Make a Heroic Dungeon Master's Guide, including the monsters for the heroic tier (also around 320 pages or so).
That way, customers can buy the game as they go along, and the books have a broader variety of material for what they're actually playing at. Having only two core rulebooks might also make people take more of a look at DMing since the investment is lower.
Sell further Player's Handbooks and Dungeon Master's Guides for the paragon and epic tiers, probably about a year after each other. That'll give people time to get their characters leveled up and further time to test and refine the content. (Is 4E still notorious for sparse content at the epic tier?)