From what we know of the upcoming Universe line so far, it'll consist of deluxes and ultras (with voyagers and legends worked in there somehow) and have an emphasis on realistic vehicles for their alt modes. While I'm more than happy with whatever we'll be getting (wave 1 looks absolutely amazing, btw) this approach seems problematic to me; first of all, they're not using the most readily affordable size class, and not all the Transformers turned into realistic vehicles (or even into vehicles at all).
While I'm not expecting anything like Dinobots or whatever, it seems to me they could easily kill two birds with one stone here. I imagine the rationale behind focussing on real world vehicles is because they generally sell better; well, why not group all the not-so real world or non vehicle Transformers into the smallest price point? (think kinda like the Real Gear figures from the Movie line). Less cost per figure (less plastic, less packaging, presumably less work to design) and being at a lower price point they'd be an easier sell for parents and such (not to mention it would offer a low cost alternative for anybody who wants a TF that isn't a car, truck, or plane).
One might raise the argument of scale; that one of the smallest Transformers -former minibot Bumblebee- is already in Classics as a deluxe. Well, lets look at who would be candidate for a basic: the (former) cassette Transformers, for example. Obviously cassette alt modes wouldn't work out here... why not go the route they went with the Movie Real Gear figures and base them off hand held devices (but with the added incentive of using established characters like Ravage and Rumble)? Hell, Booster was practically an updated Laserbeak in the first place. Another candidate for the basic scale would be the Insecticons and the Sharkticons. They were generally shown to be pretty small compared to other TFs, and while popular with G1 fans, this price point would make it easier to build up an army of them.
Other possibilities could be smaller characters like Cosmos or Wheelie, or even non-show characters like the Jumpstarters (no, they wouldn't still have to be ridiculously simple).

 

I think that's a great idea. I would love to see some Basic/Scout-sized figures in Universe 2.0. And you're right, the Cassettes would be perfect candidates. As you mentioned, they could be done in the style of Real Gears. Boy would I love a Classics Rumble, Ravage, and Ratbat.

Considering that so many of the Cybertron Scouts are already homages to G1 minibots, they could even get away with remolding a few of those. Much as I would like for all of the G1 minibots to be upgraded to deluxes, Botcon Huffer kinda blew that already.

The Insecticons would also work fine as basics, I think, since they didn't have "vehicle" modes that would need to seem in scale with anything. And they were never portrayed as especially large, anyway.

And yeah, characters with "Cybertronian" modes like Wheelie would be fine at a smaller scale, as well.