It could mean any number of things. Could be a new map/mode for 5 or mcc. Could be spartan assault type game, could be beta for halo 2019. Hell it could be a lie. 

But I do agree. 343 is too big for them to not have something this year. Also anyone notice that 343 is on a hiring spree right now. All kinds of job openings. Lol like they arnt big enough already.

I see this happening
SoT: March
SoD2: May
Crackdown 3: June
Banjo 20 Anniversary: August
Forza Horizon 4: September
Ori: September
AAA game(maybe Halo spinoff): October

MS need to have at least new IP surprise this year and bi announcements for 2019 or else this years E3 will be a repeat of last years where the only new things that we got were Indie games.

Do you guys think that MS should call up CliffyB and try to work with him again, or do you think that he burned that bridge? One game that flopped doesn't make him a bad Developer/Game Designer.

Why people ask for new IPs from Microsoft the most? They work on new IPs as much as Nintendo for example, if not more. It is just that Sony and Nintendo has the fan base to support these new projects. Sony has a diverse base that will help on increasing the chances of them becoming a commercial success. Nintendo has an extremely loyal fan base that mostly support whatever they come up with, and they deserve this.
Microsoft came up with or helped funding Ryse, Sunset Overdrive, Quantum Break, TitanFall, Sea of Thieves, Ori, Cuphead, ReCore and many other smaller titles.
That is at least 8 IPs in 4 years of Xbox One life.
I got bored of people asking for a new IP just for the sake of it. I prefer they spend this money on reviving loved franchises that weren't a commercial success, like Halo Wars 2. Instead of spending extra effort on new IP, I prefer to see these effort go to a sequel for Alan Wake, Sunset Overdrive, Kameo, or any other similar franchise.

I hope the sixth game is a surprise exclusive in the caliper of Rise of the Tomb Raider, Splinter Cell for example,  that would be a dream of mine. 
That would be a very good year and a well spread schedule.

I personally don’t see Ori releasing this year despite MS claims that they won’t be announcing stuff too early anymore. In my opinion the earliest possible release date is H1 2019. The reasons are obvious: 1) Last e3 trailer didn’t have any release date 2) The game didn’t even have a level designer up until some time after E3. This suggests that it is too early in development and probably Moon studios don’t have anything except the trailer right now. We all know that MS didn’t have a lot to show last E3 so I think that they’ve needed something positive to show and decided to tease new Ori game. 

I would probably like to see borderlands 3 as a possible timed exclusive. Would be nice get for MS. Though I don’t think we will see some third party content exclusivity on Xbox anytime soon. The situation right now is that publishers simply cannot ignore PS4 userbase. So such deals are very expensive. Looking at last year it seems that MS can’t even afford marketing deals anymore. So at this E3 the only third party deals we will see would probably be the indie ones just like last year. 

yeah I don't see why Sony should end this generation in the next two years when the PS4 is selling so well. On the other hand, Nintendo did the same to Wii, which turned out to be a disaster.
Microsoft releasing a console before Sony would mean that it's probably underpowered and probably more expensive than the console Sony would release a year later. Also it would get cannibalized by PS4 sales.

The best thing would be releasing the system at roughly the same time as Sony (or even a bit later if it's not a holiday release) with at least as much power and at least $50 cheaper.

Also I need to admit something shameful. I found some nude mods for Skyrim SE on Xbox and installed them. It's Fallout 4 all over again!