I understand that. I guess the question to explore is can you contractually bind yourself to make an offer in the future. Do you think it's never possible to do that, or just not possible in these circumstances?
AFAICS yes, you can certainly contract with A, promising that in future you will offer to contract with B. And B could be 'everyone'. You could revoke your offer to contract with B, but then you'd be in breach of your contract with A.