That is essentially what Daqri has done in the industrial sector:
http://hardware.daqri.com/smarthelmet The reason Glass flopped is because the technology really isn't there yet to do what we feel these devices ought to be capable of. Batteries are probably the biggest culprit in all of this as they are inherently governed by the laws of physics rather than moore's law so we see marginal gains rather than exponential.
By accepting these limitations we can create products today that live up to the consumer expectations in terms of capabilities but at the expense of conceding that the form factor will not be a "discrete" wearable but rather something that favors function over form. Daqri and Hololens come to mind.
While it would be possible to do the same thing with a bike helmet I just don't think the market for it would justify the design costs. Designing a good helmet is already difficult enough and you will immediately alienate some large segment of the market in the process of balancing weight versus ventilation versus aero. Assuming you get it right, you'll then have to battle the sticker shock as your msrp now has to account for helmet + display costs.
Considering the skepticism that many already have for these kinds of products, e.g. "a solution in need of a problem", you'd
really have to deliver on the user experience in order to justify higher costs.
edit: You probably were talking about just mounting it
on a helmet rather than integrating it
in a helmet. It's a possibility but the compatibility and/or general clumsiness of it would probably outweigh the marginal gains.