What's more than likely going to happen is that this will be last Mass Effect game. Just saying because a lot of people I know don't play Mass Effect or don't like it, also it just seems that there really isn't that much hype about it.... On the other hand AC is at their prime, what's probably going to happen with AC is it will be their last game with Desman, Ezio, Altiare and who ever is the new assassian (probably spelled all those names wrong) as their characters for this trilogy.
I'm not saying AC is going to be popular forever but they still have enough hype to push out a few more games. Or what they'll do is make a few spin off games like they did with Brotherhood. This is just what I think is going to happen after talking to my one friend who is all into these games just like me. So with all his being said this is just an opinion. Hopefully both of these games and they're developers do whatever they think gamers want. Also I hope you find this a bit helpful.