to be honest I don't remember anymore why I think there will be 5 updates (6 considering this) or the author himself said it or I read it somewhere on the forum. if you know, please tell me. Just considering the perks (I understand that they were at the start and it's not a fact that they will be added, but they sound interesting as content that could be related to Asuna), I would also really like to get a few sex scenes with Asuna at work (since one of these is already on the loading screen in the second part) and I also thought that all loading screens would be somehow integrated into the game, and considering your answer that there may not be battle scenes, this sounds discouraging. it's just hard for me to assess how successful the game is in terms of money and whether the author is in a hurry to finish it (or is it just rumors, and in fact the author hasn't said anything about it at all, I just recently joined the community for this game and started discussing it, so maybe I just don't know much because I haven't spent much time on the forum) just from what I see on the forum, there are practically no people who want a quick end, and most are ready to wait for the game to be more complete and finished.
And even taking into account this update, 4 scenes that were added to the room of memories, 2 of them are extremely boring (and one of them is only half animated, and the second is not at all (it seems like the first time this has happened) and judging by the room, there are only 18 scenes left (of which it seems to me that the maximum will be sex scenes 5-6 (which is extremely little)) considering all the potential content, this is extremely little
In regards to the 5 updates thing and whether or not the author said it, I don't believe they did.
My understanding on the topic about 5-6 updates left until we're done has more to do with people making guesses based off some things Fujino has said and the general trend and/or pattern in which Fujino has been updating the game.
1. People refer to how Fujino does not intend on making a Part 3
2. Each update generally increases the number by 0.05, and there's only 0.25 left which means 5 more updates after the most recent one.
3. You'll notice a bunch of people constantly arguing back and forth about the game ending soon or not; the general conclusion just ends up being that the number is arbitrary and people freaking out and being antsy while waiting for each update every month.
Part of the reason this topic also gets discussed often is basically like how you said; based off the content that is implied to happen there's like not enough time to accomplish all of it in what we would hope is a satisfactory manner in 5 more updates. For those that didn't look at the perks list, I'll just put the rest in spoilers.
Anyways, it's possible some of these scenes will mix with each other and speed up the story, but just the snippets I put here, already sound like they'll take up a lot of time. The reason why is because we still have a bunch of loose ends with the Ritual, the main plot, Sinon, and Suguha. Technically Alice is a loose end, but her story is probably effectively over and she's just around for sex scenes and to maybe make Kirito fall even further on his own side of the spectrum.
Some other stuff that's nowhere near complete would be the prurience value. The value was at 49 if I remember correctly when this update started. Fujino probably intends to make it hit 100, and well we're literally only halfway there. I think it hits like 55 or around that number by the end of this update, but that means there's a lot of work left to increase this value even further. It's possible the value will increase when Kirito looks through the office computer and see Inoda and Asuna in the hotel, but it's just Kirito's own corruption value that usually increases when interacting with all the other girls in a sexual manner.
So yeah the number is arbitrary and it's honestly hard to gauge when the game will end. I agree that there seems like too much stuff left to do. But I don't really worry or care about what that's going to be like until Fujino starts mentioning we're at the end, or that it's pretty obvious we're at the end.
. Because she's already trapped, she's under the hypnosis of the guy from the council, and even in this update, if you ask Kirito for more information, she'll say that for some reason she doesn't remember the details. After all, he was going to use her to lure Kirito to a brothel and set him up. But with Sinon and Sugu, it's a different situation. Sinon is probably the most at risk, because in this update she saved Kirito, and the guy said, "I only know one woman who can do something like that." So he'll probably take revenge on her for ruining his plans. And Sugu is somewhere in the middle, because of her connection with Sinon, there's also a chance that she'll get it, but for now, everything's fine.