I honestly think that is how CRPGs are always going to be in terms of popularity. How popular they are is going to go in waves and I think Obsidian left the space after Deadfire because:

1. They botched the launch. I didn't play at launch but I heard it was bad. Really bad. I have played the game since they fixed it up and I honestly think it is great.
2. Player burnout.

cRPGs are probably my favorite type of game, especially when they blend in at least reasonable levels of tactical combat. But they are a grind. A huge, huge grind. So when a great one comes out and gets ridiculously good reviews it grabs the attention of gamers who have never played a game in the genre before. They will usually play the 100+ hours or more it takes to truly beat a cRPG and then they want more - because cRPGs are awesome. But eventually burnout sets in because for a lot of gamers that is a big deal.

This is also not just the turn based/RTWP genre either. The Witcher 3 was a great, great game... but a super small percentage of people beat it due to how long it was. I think it is why you saw CDPR switch gears to a shorter main story for Cyberpunk 2077. I think it is why you'll see games like Starfield, God of War: Ragnarok, etc. start to settle in at that 20-35 (35 at the very high end) hour mark for the main story of their games. Because that is the sweet spot for most people.

cRPGs like... never hit that sweet spot. They are always massive, always take a ton of time and the barrier to entry into the genre is usually way higher than other games. I hadn't played a cRPG in years when Divinity: Original Sin 2 came out. I picked it up and was a bit overwhelmed at first. I was like... WTF is going on with all of these systems? Then I figure it out and fell in love with the game.

That is to say... it is tough to give the cRPG genre the AAA treatment over and over. There is an extremely loyal fanbase in the genre that seems like it will always make your game do okay, but it is extremely difficult to make the games a blockbuster hit. I think devs can cash in big on a handful of them, but after that player burnout sets in, a major release in the genre flops and the devs go elsewhere for a while.