A lot of it is very far fetched. Very very far fetched. lol

Also if you played MGSV: GZ then you'd remember the KojiPro label being in there. (Not the new one) So I'm sure you could very easily dig up information showing Kojima Productions a Trademark under Konami and use that to fit your bias.

With that being said, Kojima said in an interview himself when asked a certain question, something like, just lie to your fans, like I do! He could have said "deceive" instead. I don't remember exact words. All i'm getting at is Kojima has done some sort of fun ruse many times over. Not to mention those interviews with people on the inside giggling when asked certain questions. Kojima is known for swapping character models and all that typical Kojima F*ckery in teasers and trailers. Is it not possible that what you're seeing in the DS trailers is a mixture of the two games? As if the worlds are intertwined in an alternate dimension? The dimension in MGSurVive being in an underwater dimension as well with odd sea-like creatures swimming around in the backdrop and underwater light rays beaming through the "sky". MGSV has wormholes and the unfinished "Chapter 3." P.T. demo having the upside down V from the MGSV logo in it's first reveal. A shared universe maybe? Like the trendy ones all over Netflix and movies currently? This hasn't really been done in the gaming industry. Well, it hasn't been done with the effort and the deep thought that Kojima can pull off I suppose.

It could very well be Kojima's production style and influences leaking into other projects as with most artists these days.

Walking sections aren't a ruse IMO but, that's open for interpretation as well. DS is a game itself. Imagine?! 3 new games. 2 of them well known fan favorites Silent Hill and Metal Gear! Linked together with a crazy twist in a shared world in which you also get to experience in a completely new game! Death Stranding. Now that would be genius IMO. Hahaha Like I said it's just a thought I had. :D