This gen will get interesting because it will really test the belief some had that power was somehow the sole determinant of the PS4's success.
Think about it this way, however -- if Microsoft DIDN'T botch the messaging of Xbox One, and instead released the same hardware a year earlier than PS4, without Kinect, for a cheaper price ($399 or even lower), this gen wouldn't be as lopsided, IMO. US/UK markets would have favored XB1 like they did in the previous generation.
A PS4 releasing a year later and more expensive would have still sold better in the global market, but competition would have been more fierce. And in all honesty, I don't think most consumers are able to tell a difference in power between XB1 and PS4. Same will be true of PS4 Pro vs. Scorpio. In fact, the power gap is approximately the same (900p vs. 1080p will now stretch out to Scorpio being a 4K machine and PS4 Pro being slightly sub-4K but with hardware that's capable of bridging the gap). The power difference will be less noticeable than XB1 vs. PS4 given that there's diminishing returns the higher the resolution becomes.
In many ways this is what Sony is doing with PS4 Pro -- As a gamer, I wanted to see a slightly beefier machine at a more expensive cost, but Sony probably made the right BUSINESS decision. I was very surprised at the $399 cost and only $100 difference between the slim. This makes me think that the PS4 Pro will likely be a very attractive choice rather than something merely for a niche enthusiast crowd, and will probably represent a decent fraction of total PS4 sales (maybe 33%?) going forward. Many will probably opt for the Pro even without a 4K TV just because it's simply not terribly more expensive than the slim.
Scorpio, with more memory, larger GPU, potentially separate CPU will automatically be more expensive to produce. I feel Sony hit a very good price/performance target for their upgrade and seem to be laser focused on value like they were with the original PS4, while Microsoft may have gone overboard in order to appeal to a very niche market.
I guess we'll see what happens, but my bet is that PS4 Pro will be far more commercially successful.
I think the specs and focus of the Pro pretty much ensure that there will be a generaltional leap plus cutoff. Plus, Verendus said as much in his truth bomb of a post.
Of course there will be generational leaps going forward. I do think that Sony will keep compatibility between platforms going forward, but at some point they will decide to move their first parties exclusively over to the new platform and third parties will slowly follow.
It's the same thing that happened this gen, only the transition and dev costs will be smoother since I believe Sony will try and make the PS5 backwards compatible with PS4 and of a similar architecture.