I still remember playing Corruption of Champions and wasting hours discovering shit, or there being a handful of quality games.
So, you remember the last decade of adult gaming, therefore nothing. The adult gaming scene started in 1981 with softporn, what make it 40 years old, and I've witnessed first hand 30 of those years. Globally speaking, what happened during those three decades are what I predict for the five following ones, the adult gaming scene will stay the same, because there isn't much difference between the adult games 30 years ago, and the adult games we have nowadays.
Knowing the past generally help you to have an overview of the future, it's time for uncle AON story:
The first adult game I bought was a Japanese RPG game like all the Japanese RPG adult game we actually have with RPG Maker. And I really mean the "like" part. Same mechanisms, same quality, just with a bit less color and... well, I wanted to say "a lower screen resolution", but I remembered that most RPG Maker games aren't full screen, so with the same screen resolution. There were also a lot of interactive games, a (big) bit like actual Ren'Py interactive visual novels, just with an interface that was more visual than textual ; so yeah, in a way they were better.
And of course there were many amateurs. Difficult to tell what was the proportion of professional studios and amateurs in the 80's, because it was prior to Internet. There were BBS to distribute them, but not this must share between them, so as individual you had access to just a part of the scene. And there were no easy way to get payed, what probably also limited the size of the amateur part of the scene, and the time they were ready to pass with their games.
The 90's were a turning point. Porn studios jumped on the scene and there were few games released everyday. But the quality and ambitions of their games was at the image of the quality and ambition of their movies ; some real gems, and many many cheap quickly done games. Globally speaking, the cheap games weren't really different from the HTML games using photography for their CGs. And there's a good reason for this, they were HTML games using photography for their CGs ; more precisely they where using the web technologies of this time (the, at this time, new coming flash, and the long time so forgotten similar technologies that I don't even remember their names).
But this lasted only a decade, from mid 90's to mid 00's. With the rise of Internet, came the fall of porn studios, and with them the fall of their games. Here starts the dark age of the adult gaming scene. Tons of amateurs, almost only amateurs. And they followed the trend started by porn studios, making flash "games" with their limited knowledge and drawing abilities. Since it was prior to PayPal and Patreon, getting payed for your creation was something easy, and like for games during the BBS era, those amateurs didn't invested much time in their games. There were some semi professional studios, less than a handful, but themselves weren't doing more than cheap flash games.
Those times were really depressing, adult games were 100 times worse than what we used to have, and 50 times worse than what we now have. Remember the cheapest Ren'Py/RPG Maker game you played, it was really a pure gem in regard of the games from these times.
It's only in the 10's, so globally one decade ago, that the scene rose again, leading to what we now know.
Yeah, I know, this is a bit depressing, adult games 40 years ago were already what adult games are nowadays. And there's high chances that adult games in 50 years will not be really different from the games we actually play.
What people dreaming of 4D real time VR interactive adult games are forgetting that the scene is and always was, limited by two factors:
1) Unless the porn industry rise again, professional studios will always be the exception.
It cost a lot to develop a professional game, and the income you can expect from them is way more limited than with regular games. Therefore, the most we will get from them will be at the image of what Illusion provide us ; a cheap copy of what regular games are.
2) Amateurs can only do what they can understand.
If most of Ren'Py games are VN, and most of Unity games are just a bit more advanced VN, it's not because those engines can't do more, but because they guys and girls using them don't have the knowledge to do more with them. Everything that Ren'Py can do with limited codding knowledge, you'll find it in most Ren'Py games, and the rest will be seen only when bored professionals decide to make a game. Same for Unity games, that will mostly goes as far as the selected template and plugins will let the creator goes.
Therefore, unless Ren'Py and RPG Maker successors provide an easy to use access to VR and 4D technologies, forget about them, you'll not find them in 90% of the adult games released in 50 years.
VR, yes, we will probably have it. Same for 3D games, and I mean 3D like in 3D movies, therefore images that goes out of your screen. But this will be because graphic cards and computer screens will be doing it natively. The instant you OS will be VR/3D, your games will also be it. So, yeah, we will probably have adult games that will looks like computers in Minority Report, but with the same difference in the quality that we actually witness.