For the next 3-4 years nah no problems at all. The question is a generational one. Kids who are 2-5 years old now, as they ease into gaming, will they still want consoles? Will they want specific ones? Who knows, its really hard to tell what the game landscape will be in 5 years. I think its safe to assume Nintendo is pretty safe, they have their own little bubble and they are doing their own thing. Its unlikely Nintendo will ever double their customer base or anything like that.
Sony and Microsoft, I dunno. Google and Apple definitely want a part of their customer base, its just completely up in the air whether people will see a reason to switch or not. And its not a all or nothing kinda thing, but probably more insidious: you sub to one of their streaming services, and still have your consoles. But over the years you play more on the stream platforms and less on a console. And when time comes for next gen, you decide to just stick with streaming...
I mean, they'd probably be okay with that. The margins on the hardware aren't even close to the margins on the software/subscriptions, and it carries a big risk (if your game flops, that's not as big a deal as if your console flops, which then further hurts your software).
There's obviously some lost profit for Sony/MS if they don't sell consoles, but I'm pretty sure it could be made up in software and subscriptions. Especially if it ever got to a point where you could play these things on something like a Roku Stick (as those are cheap enough that you'd easily sell more of them than $400 boxes assuming parity in the quality department).
Overall though, I don't think it's an issue. I just don't see the killer app. Like, I'm very into digital and streaming, so I'm really the ideal person to want to use Stadia, but what would I use on it? What's there that I can't just do right now on my Xbox that I already boot up all the time and have all accessories (controllers, headsets, etc...) set up on? Unless Google finds their Halo, I don't see why I would use it.
I haven't seen Apple's thing, but it doesn't sound like it's any better positioned than Stadia.