Microsoft said next gen consoles at E3 so it's probably 2 consoles. If the specs you mentioned end up being the basic model I wonder how powerful the premium console would be.

The Xbox One X is using a Mid-Range GPU with a low-end CPU.
By the time 2020 rolls around, the Xbox One X's GPU will likely be in the lower-end of the performance spectrum.

7nm is going to allow nVidia and AMD to push up performance rather significantly.

As an Xbox One X owner, I have the opposite feeling. I want new hardware already so that the technology baseline for games is boosted... That has a flow-on effect to my platform of choice, the PC.

It's a great platform and not pointless.
Backwards compatibility has been great, the higher resolutions and framerates have also been good.
But... It's still an Xbox One, I think people forget that.

False. Consoles take years of design and planning, the semi-custom chips also take significant design and planning as well.
Microsoft was thus working on the Xbox One X before the Playstation 4 Pro released.

I do not expect a massive uptick in their games output.

Undead Labs was already making Xbox games, Playground games was already making Xbox games, The Initiative is still untested as far as game quality goes, Compulsion Games hasn't released anything significant as far as I can remember... Ninja Theory is probably the biggest news piece of that announcement, but they tend to focus on smaller budget games, which is fine.

Either way, Microsoft is doing the right thing, I still want them to do more though.

I think we should nip this in the butt early. But... 16 Cores isn't happening.
DDR5 isn't on the market yet either. (Yeah I know, you meant GDDR5, but that ain't happening either.)

I would expect 4-8 Ryzen cores, with maybe 6-cores being the sweet spot, but I also believe there will be some cost cutting, like a reduction/removal of L3 cache.

GDDR6 is likely where it will be at, it not only has increased bandwidth, but it also increased DRAM density for the same cost.

The Xbox 360 launched with two SKU's. The Pro and Core models. Could be a return to form?

My main wants are:
* Retain AA battery support. (I like to be able to swap out dead batteries easily, rather than be stuck to a cable when they go flat.)
* Use upgrade-able Hard Drives.  - External drives are fine, but look gangly... And does nothing to solve the slow spinning rust inside the console that impacts the OS responsiveness.

You are thinking hardware first, but what's in it for the mainstream gamer who doesn't understand technology?

I always think of hardware first.

But the main benefit for mainstream gamers is that... The baseline from the Xbox One/Playstation 4 will be increased rather significantly, which tend to be the targets for technology/game engines.
...Remember, just because the Playstation 4 Pro and Xbox One X exist... The majority of console games are actually on the Playstation 4 and Xbox One.

I think it should arrive by 2020-2021. 

Interested to see what they come up with for the next xbox. Just don't make it as big as the vcr xbox one was. Also make sure you got some good exclusives ready for it. Kameo 2 plz

Also the memory market looks to be supporting strong increase in spec there,
possibly extending to SSD instead of hard drive, which may also be relevant to L3...
(collapsed general market is ideal for Sony/MS to negotiate best supply deal, 
enabling larger memory and/or higher CPU/GPU spec in given system budget)

https://www.techspot.com/news/76015-analysts-headed-flash-memory-price-crash.html

I don't really get the "but don't talk about hardware so much" when a new console gen is literally about HW.
If you don't care about HW, that's lovely, there is 1000s of other things to focus on if you prefer to,
but why then would you engage in discussions which revolve around HW?
It is simply impossible to escape implications of HW when discussing a new console gen, sorry to say.

Anyways, the topic is dicatated by HW suppliers (basically AMD and memory OEMs)
which look to be coinciding for meaningful advancement around 2020 time period.
Personally, I hope hardware checkerboarding support is retained even if the HW can
manage native 4K at higher quality than current gen, IMHO checker-4K is efficient enough
at delivering VERY near 4K quality (especially accounting for things like object ID masks etc)
that retaining it as option will be ideal especially for games targetting 60 fps etc.
Higher res VR at high FPS will also be significant design factor, although who knows
if either Sony/MS release new VR hardware simultaneous with new console gen release.

2020 is a reasonable date even though I would prefer next gen to be 2021