I think you're the one who's going to be disappointed if you think we won't.  Most likely not the 18 GB of RAM, as 16GB is more realistic, but the GPU will definitely be ~12 Tflops.  AMD's new Vega 10 is 12.5 Tflops, which I think is realistically what Sony will put in the PS5.  There's even a shot that they put a 15 Tflops Vega 20 in it, if it's out in time and cheap enough by the time the PS5 launches.

The most important question: Will it be able to run open world games in 60 fps?

That would be a question for each dev.  Personally, I don't give a crap if the game runs at 30FPS or 60FPS, as long as the framerate is stable and the game is good/fun.  Having said that, the PS5 will either feature a Zen CPU, my guess is a 1700, or it may feature a Zen+ if those are out in time and are cheap enough.  Even if it is just a 1700, those are significant leap over the Jaguar CPUs the current gen systems use.

if you are expecting a 60fps console gaming world then please don't hold your breath.

An of course there will be a PS5...... all its games could very well also run on the PS4.... butthere will be a PS5. Maybe 3 years into its life we get to see its first exclusives.

I think it will play all PS4 games but the reverse won't happen.

I'll tell you what DID happen. The whole Pro model, mid gen thing? It's going to hurt the PS5 big time when it launches because lots of people are going to hold off for the PS5 Pro model. So unless Sony comes out and says "there will be no PS5 Pro", they're kind of screwed. Hopefully they do that.

You're lowballing it. Generational leaps so far have been far bigger than that. Even from 7th gen to 8th gen, which people say was the smallest leap, feature for example a RAM jump from 512mb to 8GB. That's basically 15x higher than previous gen... GPUs evolved a lot as well. I don't know what the specs will be, but I'm willing to say 18GB of RAM isn't anything impossible. Actually, I'd expect something like 32GB.

yes, PS5 will launch. likely have more power than XBX.

next question!

Highly doubtful.  A lot of the people who jumped onto the Pro are upgraders.  That type always wants the best of a certain product, as long as its price isn't nuts.  Those same people are going to want to upgrade to the PS5, as well.  And gamers, in general, always get excited by new HW.

The mid-gen upgrades sure haven't hurt Nintendo.  Sure, theirs isn't quite a leap, but they have done it with every single handheld they have come out with.  GBC.  GBA SP.  DSi.  New 3DS.  Hell, those have even more reason to wait for, as they have a couple of exclusives for them the base HW can't play, where the Pro just plays the same games.

I never doubted, but I did find people calling for short gens a la smart phones rather silly for one, the market is completely different, it just wouldn't fly.

Second, while technology is moving fast, there are factors that erode the impact. For one, devs need more and more time to develop tools that allow them to take advantage of that power efficiently and cost effectively. But more importantly, diminishing returns has continued to reduce the impact of each jump.

As a result of these factors, gens are destined to be longer, not shorter. If I were a betting man, I would say the PS4 will be an 8 year cycle, with the 5 launching in 2021. The Switch I think will be either and 5 year and 8 month cycle or a 6 year and 8 month cycle, with the Switch 2 coming in2022 or 2023. I also expect a Switch Pro of sorts in holiday 2020 or perhaps early 2021, to get the Switch relatively equal to the PS4 and Xbone. I do not think we will see a Switch Mini for a plethora of reasons.

If the Scorpio (I refuse to use their rather dumb name) doesn't lift the Xbox brand very significantly, I think the Xbone line will be the last true console by Microsoft and they will transition to a more or less entirely PC focus.