I don't know how well TOD will do nor what it will look like. But Here's my hope.
First and most, like Westy said, it should offer something new in online air combat sims.
Instead of the anarchy of the MA where everyone is on their own to do what they will, TOD will offer the structured experience and immersion of a scenario without the commitment. Probably the most difficult part of a scenario is getting players to try it. But once they do, and they learn the ropes, many lose their desire for MA play. I know of many former AW and WB players who would fly for scenarios only.
Role playing games are very popular. They offer something no other game provides. Players have a focused and personal objective to build their character that is nearly nonexistant in the MA now, except for the phony rank system. I say phony because it's based only upon kills with no regard to player contributions to an objective. After all. of what value are kills if the player can return in a few minutes. In TOD kills, or simply chasing away an opponent, can determine the success of a mission. The average player has a greater opportunity to be rewarded for his contributions, while many "aces" are from the "old school" and prefer scenario play.
How many players has HTC attracted with their advertising campaigns, and how many of these stayed? We've seen the MA fill up at times with surges of new players, but soon dwindle to the same numbers as before. Obviously AH didn't provide what many of these new players were looking for. TOD can provide another dimension of game play to satisfy more players for a longer time.
But then, if players some times prefer a quick flight to the nearest furball, the MA will still be there.