Today It is possible, you can run almost any software in system unable to run them natively via cloud services.
I can run the last version of Blender (3d app) on my old computer with outdated version of openGl driver, the online run the app for me on their system, and I can use it freely but it is a little bit slower, more the a native installation.
Sony with their app "PS4 remote" we can play with the PS4 on a phone, a computer any hardware able to run app.
It will be cheaper (time consuming, components compatibility) for Sony to develop a console dedicated to run games via their cloud service, and for the companies it will cost $0 and 0 risk taking to develop a new (crappy) version of their games, because they already running on the big sister.
Business talking it can be a win-win, Sony can update their previous portable ps at almost no cost (the hardware exist already), and the game developing companies don't need to invest money in creating a "new" and weaker version of the game. Because today it is a question of time and money, companies try to save both today to make more money. If Sony find an (financially) interest to make a portable playstation they will do it, and they have at the date of today other priority like fixing some issues with the PS5 befor the launching...

A portable with PS4 power wouldnt be possible right now. Even the likes of the snapdragon 865 plus cant maintain anywhere near the sustained performance in actual applications. Shrinking from 16nm to 5nm is not going to make a 130 watt power draw go down to 5 watt.

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These will be the very last powerful consoles. They will sell well initially but slow rapidly as people finally wake up to the virtues of streaming.

Uh huh. That's why streaming services like Stadia and Geforce Now have taken the World by storm.....

Oh wait.

People said the PS$ would be the last home console back in 2013, Gamefly was pushed as the "new normal" back in 2010. Meanwhile powerful PCs and home consoles are selling huge numbers.

These will be the very last powerful consoles. They will sell well initially but slow rapidly as people finally wake up to the virtues of streaming.

There likely won't be another portable. Sony will get into cloud gaming instead, like their competition. Maybe a PlayStation Edition Xperia phone with a controller, but not a whole new console.

I believe ps4 (non pro) portable is possible. Slim/pro uses 16nm node process. Going to 5 nm should drop power usage down. Patching games to use 720p should reduce power usage even futher to make it portable.

Knowing Sony, they'll f*ck it up again like with the Vita, and left it out to die a painful dead.

Would be great to have PS4 portable! Same power and games as PS4, but hand held?