Now I'm basing this on a very small case study so bear with me.

My friends, who are huge, rabid COD4 fans, along with their friends and clanmates... haven't even heard of MW2. In fact, they didn't even know that COD4 was actually named "Modern Warfare". Everyone around me just knows this game as Call of Duty 4.

Now I'm thinking perhaps Activision is trying to separate the IP of Modern Warfare so that they can capitalize on it in the coming years and still keep the Call of Duty series afloat by itself. But I dunno. I feel that MW2 just will be missed by a lot of people who have no idea that it's a sequel to the game they've been playing. That includes almost everyone who doesn't visit fansites.

Eh, I think people will get know its the sequel. The amount of advertising and word-of-mouth it'll get leading up to launch will assure this.

They haven't heard of Modern Warfare 2? They must pay no attention was so ever to gaming news. Or the cover of their game case - it's not like it's a puzzle you have to solve here.

It's a risky move because the Call of Duty brand is one of the biggest and best-known in videogames. I think what they are trying to do is differentiate the Modern Warfare games from the traditional CoD ones. That way they are viewed as two different franchises and therefore gamers are more likely to buy both. Plus, when you continue to number your sequels in a brand up beyond like 4 or 5, consumers tend to get wary of purchasing a new game that'll be just like the last one (see Mario Party)

This way both CoD and Modern Warfare won't become over-saturated.

This is a smart move IMO. Treyarch completely fucked up W@W. Everyone I know has stopped playing W@W (except the zombie mode) and returned to CoD4. Modern Warfare is the "new and upcoming" name while Call of Duty is getting old and over used, similar to what Broncos724 said.
I don't think the deletion of the CoD title will have any negative effect at all. This game will sell a shit load . A good game is a good game, no matter what you call it.

Yes, dropping it is bad.

Call of Duty = brand power.

Modern Warfare = not as much brand power

It seems like they keep going back and forth. But I guess that they have decided to drop the Call of Duty because COD:6 would look like they are milking the Brand.

its not a bad move its actually alot smarter cause now they will have 2 franchises in one. kinda like how you have Madden and NCAA college football. essentially the same game just with a different feel and polish.

thoes who are playing cod4 will know MW2 simply by talking to other people in the cod4 online matches. people are talking about it as we speak. all it takes is one person in a group of friends to tell all there friends about the game.

if they properly advertise, it won't be a problem.

I thought it was a bad idea in the begining simply because alot of average Joe's won't know what the hell the game is or what it's prequal was...

But...Call of Duty 4: MODERN WARFARE is what arguably gave it brand power. CoD3 was ass, CoD2 was ok, but only being on the 360 didn't branch it out too much. CoD4 on the other hand, completely revamped what Call of Duty was about, and everyone realized this because, it was indeed Modern Warfare