It is not, you will not call something that is clearly not a PS5 a 'PS5'.
it's gonna use AMD hardware, it's gonna support the same APIs, it's made by Sony, it plays PS5 games... that's a PS5, no matter what revision of AMD's architecture it uses.
And how do you make the distinction when everything is cross-generation at launch?
the distinction will be that developers could make PS6 only games if they want to, but aren't allowed to make PS5 only games without also supporting the handheld with a port
If new PS5 games are required to also run on the handheld, what exactly will change in respect to the AAA biz at large, which is expected to basically support old generation consoles as development costs are getting increasingly larger and can't sustain them from completely new install bases?
the fact that we can expect a very long cross gen period is why this handheld can work out well in the first place.
due to cross gen games and due to a possible backlog of titles that can get patched, this handheld will almost be self-sufficient and will have guaranteed support by 3rd party devs
requiring to also support a handheld that is only half as powerful is absolutely doable. it's not too much to ask, as it will be less of an issue to port stuff to it than it is to port stuff to the Series S even.
What is Sony's gain in making a handheld that shares its architecture with the PS6, only to market it as a PS5? What is Sony's gain in spending huge R&D resources on what would be a complementary device (a PS5 Portable releasing extremely late into its lifecycle) that is not positioned to sell any huge amount of units? What is Sony's gain in releasing it at the same time as the PS6, if it's not another PS6 as well?
what they gain is a path forward for the PS5 that doesn't feel like it's just keeping the old gen running. this handheld can keep the PS5 generation relevant for even longer.
they could basically release "handheld games" to support the PS5 with new first party stuff... these handheld centric games then just so happen to also run on PS5 and PS6's back compat.
no risk for the customer, as support is guaranteed. no risk for third party Devs as all games will work on PS5 and PS6 too, and therefore have a huge pool of users. and the opportunity for Sony to make PS5 games still, without cannibalising their PS6 game developments, by focusing on smaller, handheld centric titles for PS5 going forward
the key thing however is catering to developers.
and no matter if you think it's worth it to be tied to the PS5 instead of the PS6, the truth simply is that requiring game pairty with PS6 would be an insane ask for developers.
I gave a conservative estimate in my last post, where I said the Devs would need to accommodate both a system half as powerful as the PS5 and one 5x as powerful... what if this conservative estimate of 5x is too low? and this low estimate already means a 10x GPU perfomance difference between the handheld and the PS6.
what if the PS6 has 6x the GPU power of the PS5? now we are at a 12x difference.
to port a PS5 game to this leaked handheld would mean cutting the framerate in half, or lowering the resolution by 25% on each axis... or maybe keep the resolution and lower a few settings. lots of ways to make a straightforward port.
now imagine a 10x GPU difference... Devs would need to somehow reduce the needed GPU resources by 90%.
you'd need to run at ¼ resolution and ½ framerate to get close to that.
so a native 4k 60fps game would be doable sure... 1080p 30fps + reduced settings. what if it's not a native 4k 60fps game on PS6 tho? what if it's a 1440p 60fps game? suddenly we'd need to go to 720p 30fps.
what if it's a 1080p 60fps game that is designed around heavy raytracing or even PathTracing? now we're at 540p 30fps, if we assume the RT hardware (which will be stripped down massively as well) can handle it.
ok, now, what if we see a game like Alan Wake 2, that pushed the PS6 to its limits? a game that is well sub 1080p in its 60fps mode, and barely at 1080p in its 30fps mode? what then? will we see 240p 30fps games then?
the hardware power difference is just way to large. and if we assume the PS6 will have 6x the GPU power of the PS5, then well... that'd be something.
and you'd have lots of people being pissed about "holding the PS6 back!", look what people said about the Series S, which only had a 3x GPU power difference to the X... and that already was lambasted by people for "holding the generation back"