Anticipating next upgrade after B&W 803 D3?

The next step depends on what was wrong with them. Otherwise you will simply be going round in circles. 

You're on the fast track to the poor house .....and where you'll not be satisfied.

+1 Kenjit

Only had them a few months?

803 D3s are not exactly base model, have you taken into consideration the countless number of factors that may be causing them to not sound good to your ears from equipment to room aspects?

Trust me, it's the room. Think about room size and treatments, if any.

oh, they sound terrific.   But looking for improvement that’s all.

As a pool and chess player I am always looking ahead a few shots and the rush when buying something new.