I give the 9th gen a 50/50 chance of happening using the current traditional model. Even anointed, with this fusion idea is looking to a different model. Sony is for the moment heavily invested in streaming and if they can really make it a viable model I can see them choosing not to release a PS5 which is merely a hardware upgrade on PS4. If Xb one sales remains mired in the quicksand of mediocrity I see no reason whatsoever for them to devote resources and time on continuing to flog this horse when their attention needs to be on their phone and tablet business. Xbox as a hardware platform is nothing but a distraction and a sideshow.

That's dumb. There are a lot of signs that point to a reduction of the market, sure. But no more consoles? In my opinion, this is how the evolution of 8th gen to 9th is going to be:

-If microsoft manages to get enough profit, they will keep the XBox brand, and keep in mind we're talking about Microsoft, if it isn't a really big profit for the company's standarts, it won't be enough. Maybe Amazon might buy the brand and change it into a multimedia device with videogames as its main focus, they'll learn about the XBone fiasco.

-Sony won't make another handheld. The PS brand is strong and all, but handhelds were never its point (after all, Sony needs to sell their mobile devices). The only reason the PSP sold 80 million units was because of the lack of competition with other multimedia devices and the hyper-healthy 7th gen, everyone bough a lot of consoles. Vita will continue to receive indie support as long as Sony keeps selling the thing, but no more PShandhelds. The PS5 will surprise everyone by being more powerful than everyone expected, but watching how expensive developing games is going to be, the graphic difference won't be noticeable.

-Nintendo will try making the first hybrid of handheld and home console. I have no idea how it's going to work, but they will deliver. The power of the machine will be better than the WiiU, but not for that much. Nintendo doesn't need a lot of power. 3rd parties willcontinue to ignore Nintendo, but a bigger Eshop and deals with smaller developers and backing of unknown titles (like Bayoneta or Devil's third) won't leave the console as a Nintendo-only machine. Maybe they will put some of their games on mobile, but something minor, enough to tease potential consumers. The Quality of Live will sell well, nothing major, it won't reach Wii's success by far. It will, however, have a lot of media coverage.

-As for other minor consoles, no idea. No Ouiya II and no NVidia Shield, the mobile devices will be capable enough to give the same experiences as those. The SteamBox will sell between Dreamcast-N64 numbers, but that's a blind prediction (I include the STBox because it will launch with the 9th gen consoles, it will suffer delay after delay).

TL;DR Consoles will sell less, but they aren't going anywhere anytime soon.