Matthew McCallum wrote:
Volumes 50 (Captain Marvel), 100 (Defenders) and 150 (Marvel Team-Up) all launched new lines. Seems safe to assume Volume 200 should be another number 1.

Since Volume 200 should be released in March or April 2013, that gives us a reasonable short list of near-term and significant number ones that are due to premiere:

Ghost Rider
Ka-Zar
Luke Cage
Marvel Two-In-One
Monster Titles

Assuming that we get Ka-Zar at some point in 2012 and another volume of Fantastic Four under out belt, I say Volume 200 is going to be Marvel Two-In-One.
I think we will get all these (except monster titles) before 200, and 200 will be Moon Knight - the start of the direct marketing era, but that is assuming Luke Cage and Ghost Rider come first.