Lack of Japanese support is definitely a huge factor, as it prevents games like Persona and Nier, but what about homegrown games like Sony has with Sony Santa Monica, Bend, and Naughty Dog?
Everyone points to Horizon as an example of a game that was done very well, and it the exception, but what makes it so? A talented team that had no prior experience making open world games took on a new project, and nailed it. The game was critically well received, and seems to have sold very well. Why is MS so afraid to do something like this? There was nothing about Horizon that immediately gave it an edge was there? GG was coming off a pretty mediocre offering in Killzone 3.
MS has to own their mistakes, and fix them in house. Assign 343 to a new project, put Halo on hold for a few years, and hit one out of the park like GG did.
Is Halo really THAT important anyway when you have annual COD, plus Destiny, Dice, and Overwatch? I mean, yeah, it's an important franchise, but will they survive a 3-4 year hiatus? I think it will. If worse comes to worse, make the new IP based on the Halo universe. Wouldn't a Horizon type game within the Halo world be fucking awesome?