Imagining changing architecture again and fucking BC again + ease port from/to PC...
This is the biggest reason it won't happen; carrying digital libraries forward is a big deal now and people expect BC native support as well. It's no longer a luxury; it's expected as something normal.
I don't think ARM alone offers the performance needed for full next-gen gaming workloads, and it's not like x86 chip manufacturers don't have power-efficient chip designs in the pipeline. Intel already have their Efficiency Cores, which they'll improve going forward (such as adding more thread support), and AMD are likely looking into something similar (though I've also heard their approach would just be more bigger cores and running some of them at low clocks, particularly when they aren't needed for background tasks...though don't CPUs already do this more or less? Not all cores run at full frequency unless the workload requires it and throttling isn't a concern).
Doing that while still keeping things x86/x86-64 means the microarchitecture stays the same, and no need to lose performance through emulating the microcode on ARM. Besides if we look at PS5 and Xbox Series, the main thing eating at power consumption aren't the CPUs; it's the GPUs, memory and storage. Particularly data accesses since those require way more energy than the actual computations (including even costly AVX 256 calculations on the CPU).
If there's anything the 10th-gen systems will focus on (architecture-wise), it's addressing data locality and latency in order to massively bring down power usage that can be better directed to arithmetic. Probably using a mixture of approaches. Memory type, for example: there's no way in hell they're using GDDR for those systems, it''s a dead end.
Serious question here. Will we have a nextbox and a new PlayStation?
Each time that they talk about a game releasing also in PC I feel that we don't more consoles anymore.
Yes there'll 100% be a 10th-gen PlayStation and Xbox. Something has to serve as a stable baseline and you can't necessarily do that on PC especially considering what we're seeing happen right now.
ARM cores are a bit more efficient, because they don't have to maintain a large set of old instruction sets. This implies more used space and power for microcode and for the decode stage.
For companies that use old software and need these instructions, Intel and AMD can't remove these instructions. So they must be kept on the PC side.
But for a console, most of these old instructions can be removed without any loss of compatibility with very old software.
I mean, that would mean something a bit more significant if Sony & Microsoft used off-the-shelf CPUs, but they both do custom designs with AMD. Meaning they can shave off certain features they don't need.
Probably can't shave off as many as they could if they went with ARM, but there are features ARM doesn't really support which have helped x86-based processors maintain performance edges, such as speculative execution (though ironically that also made ARM chips less vulnerable to Spectrum, Meltdown and such...not that they aren't affected) and I'm sure quite a few others.
Maybe the next systems can use a mix of x86-64 and ARM for specific tasks, that's what the PS4 kind of did.
Microsoft might not release any more console hardware.
Perhaps a small box (or HDMI stick) that runs a customized Edge browser for accessing XCloud games.
Maybe something that could include ML hardware to improve the quality of the streamed frames, thus lowering bandwidth requirements.
Even if they release a full bore Xbox Series XX, you have to know that the above plan is simmering somewhere deep in the MS labs for future deployment.
They're prob def doing something as you describe (and I wouldn't be surprised if that came out this generation, let alone next), but they won't drop traditional consoles anytime soon just to do so.
Streaming will be a big part of things but they're not going to give up the opportunity to get 30% off 3P software sales. That side of the market isn't going to just completely disappear and game subscriptions/streaming in particular would need to have an absolute explosion of mass adoption in order to get Microsoft to justify going only that direction.
I'm talking they'd need 15 to 20 million new subs every year...and the vast majority would need to be through mobile. If the majority are still through console then that'd suggest a lot of people still want good-enough to powerful local hardware for their games, also suggesting they are probably not streaming the majority of the games they play via xCloud (but could be using it to preview a game as a demo, for example).