Ah, so there was one little nugget (since removed) in the Google I/O agenda after all. Unsurprising to anyone who's able to flip a coin is that it appears we'll get an announcement of the "M" version of Android. As to what might come along with it, well, we'll just have to see.
From the "Android at Work Update" session listing (which as of the time of this writing has disappeared):
Android M is bringing the power of Android to all kinds of workplaces. This opens huge new markets for hundreds of millions of devices to workers at small businesses, deskless workers, logistics and warehousing jobs ...
Of course, that doesn't do a thing to tell you what will be in the next major version of Android — Android at Work is already a thing — and even then we're not likely to get more than another preview build this summer before an eventual release in the late fall, just like the L preview last year and building on the release cycle of the past few years. But the excitement certainly is growing.
Now to guess what M stands for ...
Thanks to everyone who sent this in!