Well, there's what I'd LIKE and what I'd expect/enjoy. What I'd really like would involve monsters being built slightly differently than they are, with some similarities to how they were in 4e. I'm not so much concerned with "roles" or even minion/reg/elite/solo/swarm versions - though that stuff was useful and could be done well (but perhaps to a lesser degree) in 5e. No, it's more that I like the way that a lot of monsters had a few simple, often encounter-specific "powers" (actions) that they could do. Without getting too far into the specifics (though I bet you and I could go quite far into it), it's really that I'd like anything that makes each monster feel less like a bag of HP that can do X damage. I'd like them a little more dynamic, AND YET... I don't want them to take up more space or be any more complicated. In fact, I already feel like many stat-blocks are too long and too complicated. The MMoM versions are "better", IMO, but not quite there yet. Also: Personally, I love the 4e icons/symbols over 5e's use of "natural" (read: wordy) language used in stat-blocks.
As far as what I'd expect/enjoy, I guess it's (hopefully) a step in that direction, but not a sea-change. I don't expect the use of icons & symbols, because I've read that they don't work well for screen readers, and aren't good for the visually impaired.