Ummm, where are you getting this "twice as long as the original" thing from? According to How Long to Beat, which is an aggregate archive of game completion times, the OG FF7 takes 38 hours on average for a main story run alone, 52.5 hours if you do a mix of main and side content, and 86 hours for a full 100% completionist run. FF7 Remake is listed as 31 hours for the main story alone, 40 hours for a mix of main and side content, and 69.5 hours for a 100% completionist run. That means that part 1 of the remake is smaller than the original, definitely not twice as long. 

Yeah, I kind of doubt they will be able to fit the rest of the original into 2 more remakes, assuming that they plan to continue to add new content that wasn't in the original at least. The original game is roughly divided up into 30 parts, while I haven't played it myself yet my understanding is that FF7 Remake 1 only covers 6 of the 30 parts of the original, North Mako Reactor, Sector 5 Reactor, Don Corneo's Mansion, Sector 7 Slums, Shinra Headquarters, and Escape from Midgar. So unless they cover 12 parts of the original each in Remake 2 and Remake 3, twice as many as Remake 1, it does seem like there will be more than 3 parts to this Remake. Part 2 would need to end on the City of the Ancients with you know who dying and part 3 on Inside the Planet. 

Really strong start. Could see the game selling over 20m lifetime.

Holy molly, this was an extremely strong start.

Honestly, this game deserves all of this and more.Don't know how FF XVI will turn out to be, but goddamn is this game brilliant.If they keep it up, this may be the comeback we have all been waiting for FF to have.A FF reinascense, if you will.

It's probably selling at the same pace as God of War.

God of War Sales Top 5 Million in the First Month - IGN News

https://www.youtube.com/watch?v=A3eT4KY_nxs

That's amazing, especially given the current situation.

Ye right on the money, its like 40H vs 25-30H. Depending on the playstyle ofc, but mostly it is like u said.

Well, what is it called doesnt matter at all.Actually it is better like it is now, where we have a promise of future installments. For me its like, ya know, God of War 2 and 3.

Not exactly a filler. Remake has its shortcomings ofc, but OG FF7 also had it. Avalanche is non-existent compared to Remake, same story about character deep etc.

Well 40H is around the time I think if you want to do all the sidequests.  If you want to do all the sidequests in FF7, it'd be significantly longer I think... Although a lot of that time would be pure grinding to beat the weapons.

Breaking it into parts isn't necessarily bad, but in this case, I have mixed feelings.  It means adding a lot of content, and that content is very inconsistent in quality.  There are some sequences like Shinra's HQ and Wall Market that are incredibly well done and make the narrative better.  Then, there are some parts where you're just running through tunnels as Barrett for no real reason but to lengthen the game.