LOL BEWBS
For this, I will gladly offer up my financial udders to WotC. The Draconomicon was one of the best books of 3e, and if they're going to split it up, go more in-depth, and maybe shift the focus a little bit, I'd line up to buy one after another.
The game, after all, NEEDS dragons. I want to be able to chuck dragons at my PC's basically 24/7. It also needs dungeons, but those I can randomly generate if I need to.
So in addition to dragons-as-monsters, we'll get dragons-as-setting material, and, hopefully, dragons-as-allies/PC's.
And I'd expect a host of paths and destinies and even classes having to do with mortals signing up to help, hinder, derive power from, or otherwise consort with the beasties.
When I play D&D, I want my dragons to have a massive footprint. The Draconomicon was the closest 3e ever came to letting me do that (mostly because using a dragon was such an overwrought process, and it only really 'felt right' at higher levels).
Though the argument about milking us with supplements is true, it's been true for the entire lifetime of D&D, and they usually add more hours of enjoyment to my world than they cost me to get it, so YES.