My biggest fear is that they go too far off the deep end - like creating a brand new OS that is like IOS, crippling the pro market for a while. I've been a video editor for 15 years, so basically, I'm worried that they'll release the new MacBooks (and macs) with the OS that is the equivalent to FCPX.
As most know, FCPX was a disaster for its first year, and many shops (including my own) were eagerly awaiting the new release by using outdated software (FCP 7). Once FCPX was released and was at least a year away from being ready for professional use, it kind of messed up all of our plans. So what were we to do? Either wait it out on really old software, switch to Adobe/Avid, or jump in. All three options were less than ideal.
Now that I rely on portability for my career, I really need a top of the line laptop. My 2012 RmBP is still running strong, but at nearly 4 years old it makes me nervous, and I want a secondary machine for rendering, transcoding etc. I don't want to switch to a Windows/Linux computer because I like the way I have everything working right now - changing everything is a bit of a nightmare.
I have simple needs - more power, faster processing, better graphics card, and the option for 32gb of ram. Everything else I can take or leave - OLED bar is kind of cool (but I'm not sure I wouldn't prefer F keys), I don't care about touch ID, I don't really care if it's thinner, or what colour it is.
USB-C is cool, but at the same time it's annoying to carry around adapters - realistically it will be a little while until portable USB-C drives are available that actually can take advantage of the extra speed availability. Most portable thunderbolt drives aren't fast enough to actually require anything beyond USB3.
I wouldn't mind a computer that doesn't burn my legs when it's on my lap for extended periods of time either. Extra screen real estate would be amazing (I'd love for the 17 inch to make a comeback, but not holding my breath).