Don't want to vote in my own poll, but I'll express my personal thoughts.
I have a Surface Laptop Studio but I only use the pen, I never touch the screen. I think it's mainly because I don't want to get any oil on the screen which can build up over time and interfere with pen usage (this happens on my iPad). But also the apps and much of the OS are not touch-friendly--ie. targets are too small for touch. Nor do I want them to be touch-friendly. I want targets to be small on my work/productivity device so that the screen real estate can be utilized for working efficiently. Big targets means less targets, and more submenus, which hampers productivity. And I actually wish there was a way to disable touch on my SLS because I only every touch it on accident which is never good. I've grabbed the edges of the screen trying to adjust it and accidentally closed programs quite a few times (thankfully my work was saved each time).
However, I do use touch on my 13" iPad when attached to the Magic Keyboard--maybe around 50/50 with the MK trackpad. And I should note, I never take the iPad off the MK except to draw, so it's essentially a touch laptop for me. This is probably because I don't use the Pencil super often (so oil isn't a huge concern, only a slight annoyance), and crucially of course, the UI is designed for touch. I find that touch is useful for quick taps. It's quicker than moving the cursor to the target, unless it's a precise target like placing the text cursor in which case I'd use the trackpad. The downside to touch though, is if done for too long on this form factor (as opposed to a smaller handheld device), my arm gets tired. So it's not something I'd want to do for hours of work, but for short bursts of productivity/interaction, which is exactly how I use my iPad--for consumption and light productivity. For gestures like scrolling, it just comes down to where my hand happens to be at the moment. If it's closer to the screen, I'll probably use the screen. If it's closer to the keyboard, I'll probably use the trackpad. It's kind of a wash, but I think if my MK had a bigger trackpad (mine is the older one with a smaller trackpad), it might tip a little more toward the trackpad. But all this said, touch is still just a small bonus to me on this device. I don't see it as crucial even in my 13" iPad because I always use it with the MK. If the iPad permanently fused to the MK and the touch input broke (and if I didn't ever need to draw), I'd probably be fine with it.
I'd conclude that for me, if the MacBook gets touch, whether I would find it useful depends on how I plan to use the device. If it supports pen input and I use it for work, then I would never touch the screen for the aforementioned reasons. If I use it as a lighter personal productivity device mostly without pen input, then I could see myself using touch to some extent. But two big assumptions have to be met:
1) the UI would need to be optimized for touch. Apple could probably make a touch-optimized version of macOS easily enough, but what about all the apps--that's a huge question. If the UI isn't touch-optimized (larger targets), then I would only find touch useful for gestures, but this would be pretty limited usefulness.
2) The MacBook has to have a touch-friendly form factor. If it's a normal clamshell, I will probably not want to reach over to touch the screen often. It would need to have something like that MK or SLS cantilever design. I don't think I could be bothered to flip the screen around completely if it's a 360 hinge--and I will likely always want quick access to the physical keyboard anyway.
I'd also note, I don't want a UI that switches between touch UI and mouse UI. My SLS does that with the OS (the apps I use only stay in mouse UI) depending on if the screen is in regular clamshell mode or one of the converted modes, and even after years of use I still find it jarring/annoying for UI to change and the targets to shift or disappear. Maybe it's because I don't ever make use of the touch mode on my SLS that I find the switch annoying, but I think it's more that I like consistency, so I want it to stay one way or the other.
And again, either way touch input would only be a small bonus for me, not a crucial feature. I only find it crucial for handheld devices like my phone and iPad Mini.
