I think these pro versions are a test of what a new market could potentially look like.
imo, the biggest problem with every gen is the complete reset in install base.

having a pro version allows the "previous gen" owners to play the new games at a lower resolution. This is nice for the console makers because they don't have to start back at 1, but it also limits the advantage each console maker can have over the competitor. The stronger the console, the nicer the games can look. We've seen two gens now where performance has a huge impact on which console sells more.

So, in order to have these iterations, you need to identify a balance between having a low enough threshold on new games so that older iterations can play them, but also powerful enough to outperform the other guy. I think you're right to some extent, but a new gen will always be on the horizon, because sometimes there is a leap that completely shatters a competitor, like for instance when gaming moved to CD/DVD. Who knows what new tech will do that, but it'll happen.

Considering HW have negative to very small margin then what you proposed makes no sense.

The reason for PS4Pro is PSVR and 4k tech, and Sony not wanting to lose to many customers to PC, but still they didn't promote it highly and still put effort more on vanilla (and slim at it). The second reason was that PS4 came to market not with much power since they wanted a small price without loss.

For PS5 I can see a PS5Pro, but I don't think it will ever become yearly. Sure we can have a 6-10x gap from mainline PS, and a 2-3x jump from baseline to Pro... that would seem like a continuous 3x jump every 3 years.

That's seems to be what I'm hearing here in this thread, yeah. It really comes down to assumptions that people make for the business case for hardware manufacturers, where the maximum profits come from either:

1) continuing the "space race" and focusing on external factors, such as beating out other competition for power (former camp)

2) focusing on internal practices to make the whole process more lean (latter camp)

I can see credibility in either. It really depends on risk/profit analyses, at the end of the day. We don't really have enough information to confirm one or the other. 

I'm with you on this one. Fine with performance levels as they are now for the PS4/PS4 Pro. I'd rather see 2020 as the year the PS5 launches though.

The leap between last gen and now wasn't that big, Sony MS played it very safe and they made money with the hardware pretty fast after the release (the fact that we have a Pro/XBOX should also be a hint).

Small jumps are enough, they need to keep the prices down.

PS5 will probably launch at 400$ too.

You expect it to, yet CRI hasn't mentioned anything of dev kits or the game going anywhere itself.

While the next generation may not be a big step up since we are sort of at a technological plateau, once a breakthrough in technology happens, then there will be big jumps

OK.

Let us agree on that we disagree with eachother :)