Why does it have to look so old?
I first saw it (ICE type) in 80s - early 90s and I thinks Suzuki and Yamaha made them as well. It looked odd compared to 'modern' plasticky scooters even then. However because of larger wheel size they are stable at high speeds and so a bit safer.
What I suppose Honda will do is indeed strap the batt pack to the cargo rack but make it portable. This way the bikes won't get stolen for expensive batteries and there is no need for an alarm. You park it at work, take the battery with you to recharge it, same at home.
Using currently available tech
http://www.evcomponents.com/ProductDetails.asp?ProductCode=38120S 12s3p connection which should yield 36v 30Ah pack, it will weigh about 11kg, not too light, but manageable.
Last thing required is to clean the roads with $2 gas
