I'm not trying to be sarcastic. This is definitely a problem faced by any company with remote teams, including mine. I'm not saying any of the solutions I posited are feasible, but one day, far in the future, I'm hopeful that some kind of solution will be developed. If anything, because there is a huge market in facilitating communication between remote teams.
For some tech nerdery: Oblong Mezzanine (http://www.oblong.com/), Prysm Visual Workplace (http://www.prysm.com/prysm-visual-workplace), MultiTaction MT-Canvus (https://www.multitaction.com/products/mt-canvus side note: check out their touch tech, it's f'ing cool), DisplayNote Montage (https://www.displaynote.com/wireless-presentation-system/), as well as MS Surface hub, all the SMART products, and the multitude of other 'meeting room IWB / touch solutions' out there.
All of these centre around the concept of a large display surface, some digital whiteboarding, flexible content layout then some VC 'tacked on' so that remote paricipants can join in.
What I find waaaay more interesting is some more of the combination acoustic + CV based camera tracking that's starting to make it's way to market. In addition to tracking people, it can also track objects of interest — things like auto-framing a whiteboard when someone approaches it. Cisco is currently doing this on their collaboration endpoints with SpeakerTrack and PresterTrack and other vendors have similar tech too. There's also a solutions that are starting to use camera arrays or super wide angle sensors to capture a larger scene and extract areas of interest (https://www.huddly.com/, http://www.owllabs.com/).