You can change your pubkey anytime with a proper reason. I expect we will ocassionally have to change individual pubkeys. Certainly, I will.
Múltiple reasons here: new cold storage solution, key compromised, starting to use HD keys, switching to the same seed for all networks like I do…
Edit: also if we use a seed for all of them (NBT, NSR, BTC and in a future PPC) we can create new addresses when needed without waiting for a new public key from each member. Even creating emergency addresses with the certainty of who will be authorized to sign them.