That's the big problem with how Microsoft has constructed their studios, and one reason I was quite disappointed when they decided to go with Gears of War 4 instead of a new IP.
Effectively, Microsoft's core studios are nothing more than franchise sweatshops. They're not like Naughty Dog, Guerrilla Games, or Sony Santa Monica where Sony trusts these large studios to develop new IP if they desire and take on more risks (even if it fails in the case of SSM, or succeeds in the case of TLOU).
Microsoft treats this studios strictly as business rather than an art form, and I feel that that franchise fatigue is a real and serious issue they are facing now. Forza has never been too popular, Halo is on a steep decline, and there's no doubt in my mind Gears 4 will probably follow the same trend.
It's why I'm not particularly itching to go out and buy an Xbox One. There's no real excitement or innovation into a lot of their new IP. There's nothing like "Horizon" that they could show off and get people extremely excited about something new. It's always more of the same, by and large... there are exceptions, but generally this is a problem with their first party studios and a major reason why Bungie left, which is a huge mistake in hindsight given how immensely popular Destiny has become. Imagine if Destiny was an Xbox exclusive?