I want future Nissan electric car platforms to have:
1. A wide variety of battery capacity options to choose from.
If a platform is able to accept different sized battery packs under the car then it can bring in people into the market when they might otherwise be at fringes of the car's range per charge. For example, let's say a future leaf has a 36kwh pack, but that may be unnecessary high range for people who don't drive much and won't benefit from anything more than a 24kwh pack. 36kwh may cause some people range anxiety and 48kwh may do a lot to alleviate it. Having battery modularity will increase cost, but it can be minimized by having dealers carry cars with the middle-range pack, and requiring cars with the higher and lower packs to be ordered from the factory for the customer.
2. Means of replacing the battery and upgrading to newer battery technology and capacities.
Even if only a minority of electric cars owners would actually buy a replacement battery for the car after 5-10 years, the assurance that it would be mechanically easy and Nissan promising to support it will make everyone know that they don't have to worry if they decide to hold onto their old cars. The option should be available to upgrade the software and any hardware necessary for compatibility with future batteries technology and charging standards.
3. Ability to add onto battery capacity.
I'm not saying Nissan should produce add-on batteries, but instead to make it feasible and easy for add-on batteries to be implemented. For example, thought should be put into making room in the car for storage of add-on battery packs, such as under the rear passenger seats where it won't drastically affect weight distribution, or possibly making room in the car engine bay (I know the leaf has a lot of spaced out parts that could be compacted together!) AND also making room in the trunk so add-on batteries can be placed in the front AND back to redistribute weight as necessary. For the location or locations of add-on batteries, there should be pre-wiring and standardized connectors, and bolt-down locations to secure the battery pack to structural members of the car. There should also be software to control the charging and discharging of the batteries, and properly displaying dashboard battery information after the add-on.