It would have to be Gen 8 in order to have a shot at claiming the title of "best selling game of Q4 2018", because the spinoffs like the Mystery Dungeon series won't have a shot.

Damn, forgot about that. XD

Given the lifetime sales versus sales in the first quarter...here is the gist. 

Red Dead R. 1 sold about five million total in its first quarter, and in a year about eleven million. Headaches of different release times aside, I think one can comment on a 6-7 million sale as a fairly decent estimate no?

Now....there are franchises that can sell like that beyond such COD and FIFA titles. 

For example...Animal Crossing. It's among the titles rumored to be possible E3 reveals, and with Nintendo pushing for closer or worldwide releases it could be a worldwide release with the last year having been translating for it. 

Animal Crossing sold nearly 3 million in about a quarter in Japan and South Korea alone, and another about 2 million in America upon release. With the Switch flaring up sales (I was amazed at Mario sales for one), that could have similar explosive success when on a hotter seller than the 3DS. 

There is also a Smash Deluxe to consider. 

For refernce, Call of Duty has been the best selling game worldwide every since 2009, except 2013 (gta outsold it that year. If this is black ops 4, cod will edge out rdr2 in Q4. If its not, than RDR will edge out cod in Q4.

Regardless of all this, RDR2 will win lifetime no contest.

Right! I think we should do predictions like this after E3 cause some major games haven't been announced yet. Pokémon/2D Mario/TES6/Animal crossing/Diablo 4 could sell more.

But it will probably end up being Call of Duty anyway. I don't think RDR2 can outsell, if the rumours are true, black ops 4 and on top of that if it comes out on Switch which could give it maybe a million more. Also RDR isn't releasing on PC right ?

Call of duty always sales insane numbers even though ''every COD sucks'' according to ''most gamers'' lol

Yes and with BO4 it will certainly be a big hit knowing the reputation of the first 3 Black ops games.
Although i only think Pokémon or RDR 2 could surpass it.

More than COD?I can see it in the long term, but in the first quarter?Its going to be hard.

And there is the wildcard that is Nintendo, so there is that to take account for.

Right. Cause if a 3D Mario could sell that many units on a not even 1 year old console, a 2D mario with bundles could crash everything with Japan.

I think it's possible, since people like Rockstar games, especially the GTA games. I figure something similar could happen with RDR2. COD and FIFA will be tough competition for the game.