Next gen HW, so nothing less than Zen 2 for the CPU cores, first Zen 2 CPUs will come in 2019 if AMD won't delay them further, but APU implementations suitable for consoles could come later. And as far as we know Sony hasn't even started shipping definitive dev kits, PS5 won't come earlier than 2020. But if Sony plans to use Zen 3 instead, it won't be earlier than 2021.
GPU architecture OTOH won't be a problem Navi is already light years ahead of PS4 base model GPU cores, so even a low-mid range 2020 Navi will grant the necessary performance leap for a new gen console, and more than enough graphics computing power for 1440p VR or even better, and full 4k single screen for the base model and 8k for the Pro.

I hope so.

I want my Playstation 5 as a big black ventilating powerful box under my TV, as usual.

It could happen without making power users unhappy, if the hybrid will be just ONE of the available models. GPU won't be a problem, as when undocked graphics would be scaled down, the only thing to solve is CPU power, as even disabling some inessential services when undocked, it would still need little less computing power than when docked or as the home-only version, to grant the same gameplay (some more CPU power could be saved on local multiplayer games, when undocked the console could support at most two players, while when docked they could be four, and possibly the home-only version, maybe just the Pro one, could support even more local multiplayer games, and also on VR games, the undocked hybrid for obvious reasons could support just one player, while home-only and docked hybrid could support more VR players), so, unless 2020 mobile CPU cores will be enough for home console needs, Sony could have to wait longer to launch the hybrid, that could come one year later than launch models.

I know generation leaps are fun to hear about, however i just dont see why companies dont opt for the PC route with building a Eco System. That way all they have to do is bring out Hardware advancements that dont require all the cash grab things like building entirely new controllers or them taking out features and adding new features in.
Its why Steam is one of the most successful things gaming eco systems in the world. Not only do console leaps require a massive amount of RnD cash which leads in the billions, its also the long draw out times consoles stay on the market where visusls decay alot rapidly. I am not saying build a new console every year which requires updating but bring out a mid gen jump like the X which includes the latest features with TVs and PC settings that miss out in current versions of games on older hardware.
Anyway i guess i just like having the option to upgrade rather than waiting and watching games decay due to hardware limitations.

This may be the Last Generation they will make "Next Gen" hardware

https://www.youtube.com/watch?v=9fTXyAzwqvk 

Finally wanted to buy a pro but now will wait for the ps5

Steam games, like all PC games, have minimum requirements. Just pretend a Playstation is the same thing except the minimum requirements of the game are written right on the box art.

Also, the PS4 Pro (and its poor sales) would like to say "Hello".

Its a very good way to look at it however the big issue for me with gen leaps is they force you to upgrade when you don't actually want to or not ready to. I have to go out and spend $$$ on a new console, $$$ on new controllers and cables and batteries and accessories like head sets that might be important. Plus gen leaps also mean companies take advantage of there customers by removing major features in exchange to what they see are better features to replace them with, like add in DRM and remove Backwards compatibly etc.

Its exciting at the start to hear new info on new machines however like my PC, I upgrade when I see fit and I am also able to take my library and controllers with me, I wont need to replace anything. I still use a 360 controller over an X1 or PS4 controller because of choice. Its such an amazing system to have in place.

Anyway that's just my opinion, nothing against anyone, Gens are a fun thing to look into. 

And with PC hardware lasting longer and longer... It's never been a better time to jump aboard.

I agree, I have had many debates with my friend who is a Xbox and PS fanboy who always use to argue the point that PC gaming requires you to upgrade all the time.. and the real truth behind it is that many PCs tend to last longer than some console generations. I got a good 9 years out of my PC before moving into the 10 series Nvidia, and the PC before that lasted me 7 years. I am hoping to get another 7 years out of my current set-up. Instead of buying two or three consoles, you just invest into one PC which has access to Xbox games via Win10 and PS games via PSNow. The libraries are only growing over time. 

If you take into account as well, many gamers tend to upgrade there consoles over the years, normally moving to the Enhanced or Slimmer models after 3 to 5 years while with PC its sort of like once you buy it, you don't need to spend anymore until your next upgrade leap if they ever decide to upgrade.

Its a big price to pay upfront however it all pays off in the long run, plus majority need a PC/Laptop so it doesn't have to be exclusive just for gaming. Much like a Phone, its sort of a requirement to have in life, why not make it a good one.