Hey, I am in a somewhat similar position, though down the road. I have just retired and am looking into a Masters in History for the love of it. Seems like many history programs start with teaching basic skills for historians, and not having a previous degree in the area is not a major stumbling block. Two of my degrees are in the sciences and one in business, and the schools I have spoken with haven't blinked. But then, I have 25 years of work experience behind me - that might make a difference too.
But I think you can consider yourself still a viable candidate.