What are some new features that you would like to see after the Grand System are fully rolled out?

I myself would like to see that you would be able to change the spirit origin of one or two servants and change from one class to another. I think it would be nice to be able to for example change Hakunon from being a Moon Cancer to for example an Alter Ego or similar to let people change their favorite servant from a class that they feel are inferior or to buff up another class that they are lacking in.

Some restrictions would be that if you have more than two servants that can do this, the classes can't overlap, so if you have moved Hakunon as in the example above you can not change to or from a Moon Cancer or Alter Ego. Beast Class is a no-go due to being very special and Grands are also not able to change class in any way. The feature can be refined but this is something that I would really love to have a lot.