Graphics won't matter so Nintendo instantly becomes a high end console.

Dedicated gaming devices might still be used even if it's just for controllers and convenience.

Nintendo seems fine for now because they've successfully predicted the future again.

DS embraced touchscreen and microphone games that were about to become huge thanks to Apple/Android. (DSi added a camera)

Wii was a TV-box with a TV remote as a controller, the market didn't go that way but most new TVs are smart TVs and therefore could easily become consoles. Every TV manufacturer could install their own Wii Sports if they have motion control in the remote.

3DS used multiple cameras and motion control because that's what smartphones were about to come with as standard.

WiiU thought multiple devices would be connected and would allow for streaming, extra screen(s) and asymmetric gameplay. They do but no-one takes advantage of it.

Switch is a 'tablet' (does the Gameboy count as a tablet?) built around a selection of blutooth controllers and TV docking which is one of the future battlegrounds if 5G is as fast and stable enough as promised and/or when the graphics difference shrinks.

Nintendo has and is successfully defending itself against smart devices. Smartphones, tablets, smart TVs, TV boxes. If 5G makes every device a PS6 level graphics beast then the war will be about exclusive software, controllers, friends lists/online, maybe the ability to easily switch between TV and portable, price, simplicity/accessibility, gimmicky addons, local multiplayer.

Sony and MS lose all (except online) their strengths while Nintendo's are magnified.

If we all wake up tomorrow and every $30 Android device can seamlessly stream PS6 level graphics with zero lag and zero cost to porting, who wins the console war?

Isn't the only reason there is little lag because they will do input prediction? If so that's bad. But if they can pull off no lag without input prediction, and literally any device can play any games, then yes I agree that Nintendo will slaughter the other two if these were the Microsoft and Sony from a generation or two ago. However, they have probably noticed this and that is why they are both buying up a lot of studios to have more first party games.

Air latency is not the same thing as end to end latency. Even late 3G networks already had theoretical air latencies below 5 ms earlier this decade. Speed of light and server lag are a thing even with 5G, you know.

Besides, I'm not sure precisely which point you're trying to make about Nintendo since none of the devices you mentioned have anything to do with 5G whatsoever. Not to mention a putative streaming future still depends on companies with the funding, infrastructure and know-how available to provide this service. Microsoft and Sony do... and Nintendon't.

My mom got her first smartphone last month but being elderly on a limited budget she got a track phone. She bout a 500MB data card and the updates and shit ate all her data in a week even tho she was on wifi. Sure most people playing games don't have a tracphone but some of us do. Then even on big networks like Verizon the monthly cost and data caps. When I want to watch a video or listen to music pn my phone it's locally stored to avoid caps.

You assume that 5G is used to compete against home consoles but have you ever thought that it can be used to also augment ownership of those said systems ?

5G alone won't bring you any gaming value, it only brings you data value which could be potentially used for streaming content. 5G is arguably more of a threat to Nintendo since potential customers can get a superior experience by streaming their games from their home systems (whether it'd be from consoles or not) to their portable devices over the 5G networks ...

Think about it, you only have to carry a single portable 5G device while you don't have to carry any other system including the Switch for high-end gaming purposes ... 

If home consoles are obsoleted by 5G then so is Nintendo as well ... (unless they were designing 5G modems/RF modules like Samsung, Huawei, or Qualcomm were too to have 5G capable devices)

Nintendo will be 3rd party before I even finish typing this post.

ehh.. while I agree with your point concerning data caps, the bolded is not accurate

 if the max bandwith they send (4K60) is 35Mbps, then the average bandwith is much lower than that and so is the data useage

Yes, and they are calculating with the theoretical max bandwith of 35 Mbps (for 4K60) for every single second that is streamed, which is a very unrealistic case. In reality compressed video data varies a lot in size per second based on how much the picture changes every frame (that's how today's video codecs work). If 35Mbps represents every pixel of all 60 frames send changing in every frame, then I expect at most 80% of that bandwith be used in a longer average and that's probably for games with lots of fast camera pans.

Maybe in the US. Pretty much every European mobile network have an unlimited data plan, with usually 1-2TB per month fair use policy, for roughly $40-$50. That’s with current 4G infrastructure. 5G will most certainly increase that cap.

Microsoft Azure and Amazon Web Services.

You know that all these pretty graphics have to be calculated elsewhere, right?

Microsoft already has Sony in the bag: https://news.microsoft.com/2019/05/16/sony-and-microsoft-to-explore-strategic-partnership/

A Microsoft / Nintendo partnership is also rumoured: https://wccftech.com/nintendo-streaming-microsoft-azure/