Doubtful USP!

If the USP becomes doubtful then what can be done? It causes an immense loss of self-belief when one's belief in one's core competence gets shattered. After being known for one particular domain and then being known for other can be okayish for most of us but is very painful for someone who had put his heart and soul into that. It is tough to reconcile with the loss of a particular skillset. Never mind. Every loss comes at the cost of a gain. Is it a zero sum game? Let me not rue over my brain shifting position from right to left. I always had a bit of lefist leanings.:)