Possibly. But I think iPad's problems is that its just so limited to what a real computer can do, so people just end up using their phones since its the same OS/apps. Thats probably why the bigger of the new iPhones is selling so well.
Regarding MS's issue, I think even if tablets aren't the way of the future (yet), the modern UI could be/should've been. The problem with Windows 8 was that there was/is a LOT of stuff you can't do in the modern UI. Tons of settings, controls, etc that MS either didn't have ready, or didn't want to put into Metro. And the big one, APPS. Lots & lots of them that people depend on are only avail in classic that still hasn't came over to modern. All of this stuff keeps classic mode hanging on.
Its not totally MS's fault, but a lot of it is (like avail settings inside Metro). I think in the beginning of Windows 8 they probably wanted classic mostly dead by now, but that obviously isn't happening. I just wish they weren't going so far back the other way with it now.
We'll have to see how the market develops going forward. As Yogi Berra said, "It's tough to make predictions, especially about the future." At this point, however, I believe that the idea that tablets would rapidly displace PCs was erroneously driven by the normal human tendency to extrapolate short term trends (rapid initial growth for a new market) into the long term combined with a pro-Apple media narrative and an overly simplistic view of people's computing needs and wants.
That's not saying that tablets won't be around, just that there's going to be a more complex mix of devices in people's lives than simply tablets uber alles. Which means that if Microsoft wants to have Windows scaling on a range of devices, they've got their work cut out for them. I don't envy the Windows 10 team.
So take the charms bar of Windows 8.x, or even more broadly, all the edge swipe gestures. I really do like them for the most part, and the left/right swipes in particular can be wonderfully convenient when holding my Dell V8P. A quick flick of the thumbs brings up the charms or the Modern app task switcher. But they're not perfect. My kids and I have often accidentally triggered them, especially playing games. Fruit Ninja, being all fast swipes across the screen, was particularly bad for this. That was the game that drove me to change the default left swipe gesture to be the task switcher rather than sliding in the next app on the stack. I'd be playing Fruit Ninja and all of a sudden I'd be looking at my email or internet explorer. It gets worse the smaller you go in screen size. Except for the pull-down notification added in WP8.1, Windows Phone really doesn't have any edge swipes, and I'm pretty sure that's due to screen size. That pull-down gesture for notifications comes from Android, also copied by iOS, so it's 'standard' and given the normal portrait orientation of a phone, that's probably the least likely edge gesture to be triggered accidentally. I've also run into a similar situation using a laptop running Windows 8. It had a small trackpad with trackpad gestures enabled, and I found it maddening because I was frequently getting my finger too close to the edge of the trackpad and triggering an edge swipe.
On the desktop, the 'hook' mouse motions for the left/right edge swipes are also a little clunky, and I think it makes sense to do something about them there to improve the desktop experience. There's also another oddity with the charms bar either with windowed Modern apps or snapped modern apps if the app with focus isn't on the right side. That oddity is that the charms bar is analogous to a menu bar in a traditional desktop app. However, it's more like the menu bar on a Mac where it's at a fixed screen location regardless of the app window location, rather than like on Windows where it's in the app window. And like on the Mac, sometimes I've found myself bringing up the charms for the wrong app because I thought the other one had focus. There are other things that may be a concern, like what about the near-bezeless XPS13? It can be configured with a touch screen; do the edge gestures work OK on that system? How about if a future version pushes for an even smaller bezel?
This is just my musing trying to reverse engineer the decisions that are going on with Windows 10. I may be completely wrong in my thinking. But what I see is a potential logic that edge gestures may only be workable on a subset of potential windows computing devices, and an attempt to come up with a common solution instead to build a coherent experience across the entire range.