[What feature do you want for 1.8?]

Terraforming would be amazing and building bases on other planets,capable of launching space crafts.

[Multiplayer in KSP 1.8]

KSP can have multiplayer options,in which players will have their unique ID and can connect with their friends.Friends altogether can build huge bases,space station etc. and people can make their projects under a named program. For example. building a series of launch vehicles under program named SIGMA.(just like real life space programs)

[Making KSP more realastic]

Let's make KSP more real with some speeches, fluctuating budgets in some modes, constructing bases on other planets and launching ships from their, expanding kerbol system.