I could go for as little as every 5 years if the traditional concept of 'generations' changes. Where instead of a new platform we just get a new target of power that games can harness. Where every game released is forward and backwards compatible. Basically that the fundamental platform is the same each new SKU release.

If they could do that for at least 3 cycles with a possible fundamental reboot in platform (only if necessary), I would be happy. If that just wouldn't work I would opt for 6-7-8 years between new generation releases with support for previous generation lasting 1-2-3 years.

Of course console gaming is going to enter a period of higher flux (volatility) in the next gens with dropping physical media (its only a matter of when), with streaming taking over the majority of gaming (its only a matter of when). So much of this discussion could be entirely moot when we don't even need 'consoles' in the first place.

I'm strongly against the idea of releasing iterative hardware upgrades every 1 or 2 years, to me its a horrible idea. I want to buy one device and feel confident that games are going to run properly on it for a good 6 years, not run worse and worse as each new model releases and games become less optimized since they have to target so many different hardware configurations and inevitably the older models get the short end of the stick.

Such a model basically screws over everyone except those super-rich enough to keep buying the latest iteration every year.

Alrighty, thanks. So probably add 2 years onto that to account for Nintendo being conservative, like how they used a 2015 Tegra X1 for a 2017 system release. I wonder if they'll end up having to get a custom SoC made for Switch 2, since IIRC, the newer Tegra chips like Xavier are no longer geared towards mobile gaming applications?

6 years.

7 years brings console makers enough time to profit and to carefully design the successive gen too, while game devs get a longer living platform, that besides giving them too more time to profit on each game, also allows them to develop more stuff for it, so adding further return on the investment they made to develop for it, studying it, buing dev kits, etc. and dev costs are less likely to skyrocket.

Xavier is still geared towards mobile applications, nVidia just chose to throw energy efficiency out the window with the chips it did release in order to hit certain performance and power targets for specific markets.
Chips can scale downwards and upwards surprisingly well in terms of power consumption.

nVidia will still build semi-custom chips based around it's Tegra line for various customers... And if they can reuse those designs for other devices like Shield, then they will probably do so... They might have chosen to give up on Phones and Tablets, but they are still active in this space.

The 7th gen felt like it went on too long because it was really struggling to hold up with PC ports. People forget but a lot of AAA games at that time would dip into the teens in frame rate and the sub-HD resolutions were kinda rough.

The 8th gen though has held up better, frame rate is generally pretty solid, graphics still impress and resolution is good thanks to dynamic resolution techniques. The mid gen upgrades have also been great for more visual polish and frame rates.

I think 9th gen launch specs will last a good 7-8 years as well. Maybe there will be a mid gen upgrade for those who really need those 8K visuals with 120 fps.

IMO, Xavier if ported to 5nm and with a lower clockspeed as well would be perfect for a Switch successor so long as Nintendo doesn't worry about backwards compatibility (incompatible ISA) ... 

I don't know if Nvidia likes the idea of tailoring to the specific needs of a big customer because so far all Nvidia has done recently is use off the shelf available silicon so they might actually refuse to design/build a truly semi-custom chip unique to a customer ...

Maybe it's time that consoles start including some form of expansion port, like in old days - I figure more people might go for mid-gen upgrade if there was just another box that plugs into your existing...

nVidia tailoring chips to specific customers is probably exactly what they need to do. AMD has been stupidly successful with that approach... And nVidia might be just taking that exact approach with Mariko... Which doesn't have any equivalent released chip currently.

https://www.eurogamer.net/articles/digitalfoundry-2019-switch-new-tegra-x1-silicon-comes-into-focus

Orin would be a more impressive fit though.
https://www.fudzilla.com/news/45943-nvidia-announces-automotive-soc-orin

6 to 7 years is ok to me