They've been doing it since the PS1 and have always been fine.
If anything, I'm not seeing the evidence that gives MS any advantage. Even if a Xbox 1.5 absorbs the previous 20 million, that's still less than half of what PS4 userbase has now.
Sony starting from scratch doesn't eliminate the fact they would still have the biggest mindshare going into next gen and only need to convince those same people to buy their new console.
They weren't really always fine though, the beginning of the PS3 generation proved that (despite the console starting out with PS2 BC and still having PS1 BC). Plus, other transitions have shown users are fickle when choosing their next console. By and large they don't really have brand loyalty because the only things usually connecting one console to the next from the same manufacturer is the brand name. It's probably the reason each new cycle is a total reshuffling of the deck. There's no guarantee that mindshare carries from one generation to the next. In fact much of the time it doesn't. If the PS5 starts from scratch, one mistake on Sony's part or one surprise move on Microsoft's part could totally shift the momentum like it did for Microsoft going into this generation.
Turning towards a hardware-agnostic ecosystem approach could bring some stability to this. People would end up buying into the PlayStation ecosystem or the Xbox ecosystem which would give them more to hold onto by upgrading from a Sony console to a Sony console, or a Microsoft console to a Microsoft console. I know the main reason I've stuck with iOS and Windows is because of all the software I've bought for each platform.
I feel the same. If iterative consoles happen, I'll never buy a gaming PC again.
They're basically the same thing anyway, just without the PC hassles.
Some people here say "I'll go PC then" but they would have to upgrade as often, it would just cost them more because they don't get a mass market price, unlike on consoles. Plus their non official spec would get a worse support than the official closed specs, so outside of the mods and general openness, there's no real incentive left to go PC. You'd just get less for your bucks.
This kind of consoles could actually kill gaming PCs for good because you get both consoles advantages (closed specs, affordability because of mass production and a potential small subside, ease of use / plug and play, stability, console optimizations) AND PC advantages (top hardware, quickly evolving architecture, full compatibility both backward from PS4 and forward). I suspect more PC gamers would go consoles. On a board like GAF though, you could find more people trying to go the other way. They're just not the majority.
It could really go one way or the other for a lot of people.
Since going to PC I don't think I'll ever not play games on an open platform again. The main reason I've stayed with PC isn't higher fidelity but really the increased freedom I have with my software and hardware -- the fact that I can install my games on anything I want.
Sony and Microsoft taking a hardware-agnostic approach would decrease the difference between PC and console a bit, but I personally think that if handled right it could be to the benefit of consoles. Over the years the manufacturers could eventually figure out multiple form factors that connect to the same software library (even potentially a handheld one down the line). Giving the software library a sense of permanence beyond the life of one console would increase the value of console games for me and at least make more more likely to support a console in addition to PC. At the same time yes, it would bring console hardware a bit closer to PC hardware. Probably not in-line with high-end PC hardware due to size, price, and power consumption, but the gap wouldn't be as big.
And theoretically if console manufacturers kept the architecture and API consistent things would be more stable for developers in that regard. Optimization might take more, but actually figuring out the platform might not be as hard upon the appearance of new hardware.