I don't think it would though, imo FF doesn't cater to the regions tastes anymore that's the problem. It could do 2m if on both PS and Switch but I don't see it doing 3m again until the series re-establishes an identity that the region finds appealing.

This is why FF is on the decline there, we're talking about a series that used to be comparable to the likes of DQ, MH and such, those numbers aren't bad yeah but it's still a continued downward trend. 

Oh LT sales…. That’s a good one. 60/40 chance it will, i think. It has done ~ 1.4 so far in the year. The holidays still ahead. 

Think if Square-Enix wants the Final Fantasy brand to stop declining they're going to have to eventually start rebuilding an audience for the main series on the Switch platform (probably the successor at this point, but all the same) in addition to Playstation. Playstation-only is not helping the brand. 

Like I would say FF17 should be a PS5 + Switch 2 minimum, but probably XBox in there too. 

Switch in beast mode (for the sales it should had in this point in it's life). Didn't expected that.
It has a real chance of reaching 4M this year.

True, but it is only availiable on the PS5, which has a very low install base. FF7R did over 1 milion in Japan (I believe) which was on the PS4 console with a much larger install base.

It has had a good first week worldwide, so I hope it can continue with good momentum.

Final Fantasy XVI would need a 67% digital share to have cleared the 1m mark in week 1 in Japan. But I don't think that's likely with worldwide sales having crossed only 3m, because that would mean that the game has had a weak launch in the USA and Europe. It's more reasonable to assume that Japan is declining while the series is slightly improving in the West. Regardless, this is by far the best debut for physical software sales that the PS5 has seen and there won't be many games this generation that can surpass it; Monster Hunter World 2 and Dragon Quest XII are sure bets I'd say, but other than these two I can't think of anything else right now.

As for Switch sales, attributing this boost to last week's Nintendo Direct isn't farfetched. We've seen it happen before with other megasellers where their announcement already caused an immediate boost. SMB Wonder is a big deal.

They should at least make spin offs focusing on Switch. And make them turn based. 

Daisy being confirmed as a playable character in a mainline Mario platformer.

Final Fantasy is doing totally fine worldwide though. It had a much better launch than all other PS5 exclusives, aside from GoW Ragnarok (holiday bundle launch) only in its first week and is the sixth best selling PS exclusive at launch. It also sold more units than HFW at launch, which is now at around 9 million.

This game has a lot of potential to reach the 10 million mark on PS5 alone. Square also got a heavy bag of Sony money and plenty of Sony support during development. Furthermore it could also get a bundle for extra sales. So I wouldn't say that's bad perse or that FF is anywhere close to being irrelevant.

Next year it will also get a PC port, so I don't think this game is doing that bad at all, it's just not doing great in Japan (which is a much smaller market than US or Europe). The Japanese market is basically dead for PS software to begin with.

FF7 remake also is pretty close to the 10 million mark and will most likely pass FFXV worldwide. So a game being (semi) exclusive doesn't have to be bad for it's sales or value. Especially if someone is willing to pay a big check for it.

Square has always wanted to make Final Fantasy games where it can show off the most graphically.  If they weren't so fixated on the capacity of cd's to produce fmv, they might have stuck around on the N64.  I don't think Nintendo will ever see a brand new mainline Final Fantasy unless the Switch 2 is significantly more powerful that expected.