Sub_Level
wants to fuck an Asian grill.
It's not salvageable because a giant ship crashed into Manhattan offscreen and killed thousands of people, the president died, the US government is obviously guilty of conspiracy with no hope of a cover-up, etc. Everything is upended and nothing can be the same. It also takes the piss out of Metal Gear Solid by exaggerating all the game's flaws: Convoluted and silly plots with the Patriots, cartoonish and inexplicable villains in a serious setting with Vamp, long and pointless and even nonsensical codec conversations, etc. I legitimately cannot figure out how to make a decent sequel to it because the entire point was that everything was fucked up. You can make a game following it, sure, but it's not going to be able to address it solidly.
It's quite simple: be selective with what you address. Or set the game 100 years later. Or retroactively make it a VR mission or never speak about it again to maintain a sense of ambiguity. You're assuming that everything MGS2 did would have to be taken literally in a sequel, which is the exact mistake MGS4 made (although not the only mistake, because even a literal followup of MGS4 could have been done better).
Please explain to me what MGS2 did to force MGS4's hand at
having Naked Snake's support team become the original Patriots. Or Raiden becoming a ninja. Or Vamp being powered by Duracell Nanomachines. Or everyone for that matter being powered by Duracell Nanomachines. Or FOXDIE becoming dormant and lethal and dormant. Or a young savant loli creating a virus that solves like half the conflict in one fell swoop. Or Big Boss actually being alive. Or Mount Snakemore. Or Naomi's cleavage. Or the latter half of the B&B fights being softcore pornos. Or Ocelot utilizing a self-imposed mental doppelganger. Or e.t.c. e.t.c.
With regards to the Patriots being silly, the villains being cartoonish, and the codec conversations being nonsensical; absolutely all of those are relative. The conversation with President Johnson about the Patriots and subsequently Emma about the Y2K countermeasure were really cool. I thought Fatman was an awesome and funny character. Vamp was not terribly different from Grey Fox jumping multiple stories in the REX hangar. I don't recall any of the codec conversations being "nonsensical".