One thing that isn't mentioned is the processor. I'm hesitant to buy the S5 as it's got the same CPU (performance anyway) as the S4. I'm hoping the S6 will give big speed gains that will help with longevity.
Fair comment, and in the post you quoted that from I believe I said I think there will be a performance upgrade. It will have to be balanced against battery life though, which will limit any speed increase I think, especially if there is need to make the S6 24 hour capable for sleep tracking, remembering current models are only rated for 18 hours.
The S5 didn't get a processor upgrade over the S4 - why was that? I'd have to say it was for two reasons, 1. that the S4 was fast enough, and 2. that the S5 is already pushing things with battery life by adding AOD, so they didn't want a more power-hungry processor making things even harder
when they didn't need it.
I'm sorry I don't remember from your previous posts if you already have a Watch or if you're looking to buy your first, but in case you don't currently have a Watch at all, what I would say is that the S4 and S5 are plenty fast enough.
Could they be (noticeably) faster - certainly, and it would probably feel sluggish to go back to the current performance after using a faster Watch, but they don't feel slow. I doubt WatchOS7 will change that.
With the S6, if Apple is looking to make sleep tracking and/or blood oxygen measurement a key challenge they'll be up against is battery life again. Same as with the S5 they'll not want to add too much more performance as that will just make it worse.
I don't think they'll go a third year with the same processor however, and maybe they have been working on something with more power and some fancy power management as well. Even so I just don't think that they will have sufficient battery power available that they'll go nuts with the processing power upgrade, especially when nothing the Watch does requires a lot of processor power. The iPhone gets ever more processor intensive computational photography improvements and is used for gaming so arguably
needs step changes in CPU and GPU performance that the Watch doesn't. The Watch needs more electrical power to drive more hardware and to go for longer, not to push more bits.
Lastly, contrary to a lot of what I see posted on here, Apple wants to tempt people to upgrade with new features before their old hardware needs to be replaced, not make people grudgingly shell out because they think their old Watch is no longer functional. Even more so they want people to be happy that their two year old Watch still gets new features for free - that makes them loyal and more likely to upgrade at some future point.
If a customer gets the impression their Watch has been made obsolete by Apple while they still consider it to be within a reasonable lifespan they are likely to be unhappy and perhaps not bother with a new one at all. It would also push even the real die-hard fans more toward the cheaper Alu models rather than pay more for the Edition, Hermes or even SS if they can't be used for more than a year or two, and I expect there is more margin in the higher end models than the cheaper ones.
Overall I absolutely expect the S6 to be better than the S5, but I'm not sure from what I am hearing that it will be
much better.