yeah sure they have art and story from the original MG, but MGSV added some retcon to the lore. i don't know how the hypothetical remake is going to incorporate the updated canon without direct input from Kojima.
i mean one of the reason i think MGS: Survive was a failure was because of it's straying from canon that fans disliked, and any remake would probably be treated the same without the involvement of the original creator. Just how I feel about though. Others may feel different.
MGSV didn't really retcon anything to me as the narrator isn't reliable. I wouldn't have had a problem with V retconning stuff, but as it is, nothing in the game can be taken at canon.
The biggest thing is the nature of Venom. Most people who played the game bought that Venom isn't Big Boss, and I know Nojima with his novel canonized this ending.
I won't list everything that doesn't add up within the continuity of TPP alone, but to me the biggest argument is the novel 1984, which is a huge inspiration for this game.
Mission 46 is called truth. In 1984, Truth=Lies. It's absolutely impossible for me with that in mind to take Mission 46 and all the Truth tapes for granted.
My take on the game has been the same for 5 years: Venom is Big Boss. He is just suffering PTSD. All of what happens to Paz is what actually happens to himself. He convinced himself he is the medic to try to forgive himself for Paz's death, but also for Chico (who is barely mentioned in TPP which absolutely beyond comprehension when you've played Ground Zeroes). It's clear to me he can't cope with reality no more and denies his own nature.
I'm saddened we most likely never will see the proper ending.
MGSV isn't the missing link. It's a fantasized link from a destroyed mind.
I'm still waiting for the real Metal Gear Solid 5, with the real Big Boss downfall and all the things we should've had in the game (Franck Jaeger & Sniper Wolf recruited by Big Boss, Solid Snake facing Big Boss, and so on).
It's still an incredible game to me and worthy of the title "The Phantom Pain". I still can't get over it 5 years later, and Kojima's complete lack of communication and information ever since then blows my mind. Shame he completely lost himself with Death Stranding. I'm still hoping for a proper come back on the Metal Gear saga. It's his Star Wars, he has to complete it himself. No one else can.