I don't think Honda would intend that bike for serious off road use. If it's CRF250L based and fitted with indicators as in the pictures I'd expect Honda to spec it with a competitive price point and volume sales in mind i,e, as a styling exercise primarily for road use like they have done with the CB500X.
It does look a particularly attractive styling exercise though and if Honda can keep the price within 10-15% more than the CRF250L I think they'll sell plenty.
Of course time will tell which of us is right.
"Serious off road use" is a relative term... if you mean actual off road competition, such as Baja 1000 desert racing, of course that's not what this CRF250 Rally would be intended for.
But on the other hand, just like the CRF250L that it is based on, it is clearly designed to be ridden off road at least as much as on road... hence the term "Dual Sport". In other words, bikes like the CRF250L (or this proposed Rally version), just like all of the Honda XR's with DOT lighting that have preceded them, were not designed or intended to be on-road bikes as they're primary use.
Going back nearly five decades, the Dual Sport category has it's roots clearly planted in the off-road world. And that hasn't changed... the main thing modern D/S bikes have in common with street bikes is DOT legal lighting and mirrors. Beyond that they are as different as apples & oranges.
So no, the CRF250 Rally is not "a styling exercise primarily for road use"
. If it was, Honda would not have fitted it with 10% on-road/90% off-road knobby tires, would they?
As for the CB500X, that bike is not in any way shape or form considered to be a Dual Sport bike. The so-called "Adventure" category is more of a marketing gimmick than anything else. For starters, the CB500X has only half the amount of rear suspension travel, and only 2/3 as much front suspension travel as compared to the CRF250L. I won't even go into the huge differences in frame geometry between the CRF and CBR/CB series... again it's apples & oranges.