Amazon has historically had the capacity to be ruthless. For example in it's fight against collecting state taxes, it shutdown third-party sellers in states that introduced laws requiring Amazon to collect state taxes. Eventually Amazon lost that battle, which paved the way for Amazon opening more fulfilment centres in more states.

I wouldn't be surprised if Amazon announced the closure of this fulfilment centre. It would seem dramatic but if it kept other centres from unionizing I could see Amazon taking the short-term discomfort.

I don't know what Amazon's calculation will be in these circumstances. If Jeff was still in charge I reckon the fulfilment centre would be closed down.