Dear Lord. I'm on a late 2009 27" top of the line (at the time) iMac, and last year, I finally had to give up on the magic mouse as it kept dropping the bt connection every 15 seconds or so. Nothing I did would fix it. So I'm now humming along with a no-name wired mouse - so relieved not to have to worry about dropped connections, and not having to charge anything either.
The Touch Bar looks like a great thing, but I dread anything Bluetooth. I can just imagine the immense frustration as it drops connection at just the wrong time - and if a lot of data needs to go back and forth, I can imagine the battery life would be depressing too. And Wi-Fi - I get my internet on the iMac through an ethernet cable, thank you, so no problem there, but looking through threads here, it's not rare to see complaints of constantly dropped wi-fi problems persisting through successive iterations of the OS. Bottom line: any kind of wireless connection is a potential weak point, and I would not be super excited to have to rely on it for mission-critical applications... that way lies frustration.
By all means, Apple, please implement Touch Bar for the iMac - just could you please make it so I don't have to develop ulcers due to non-stop frustration with dropped connections?