I'm not a predictor, so I haven't voted, but presuming that by a "hot dog" you mean a lightly spiced sausage inserted into a bun, then yes, it is meat between bread, and therefore a sandwich. As it turns out, I had a similar conversation with a co-worker recently. I had purchased a "smoked sausage sandwich" from
a barbecue truck at our work site. This sandwich featured about 8 ounces of sausage and 2 of bread, and I commented (not as a complaint) that this was pushing the definition of a sandwich pretty hard. He raised with a "pastrami sandwich" he had purchased at the Carnegie Hall Deli which had about a pound of meat and perhaps only one slice of bread.
Personally, I don't consider a sandwich to be properly complete/balanced unless it has similar amounts of meat, bread, and fleshy fruit/vegetables (Tomatoes, sauerkraut, and mango salsa all count, as well as a few other ingredients). Therefore, IMHO, a hotdog with bun is officially a sandwich, but not a GOOD sandwich unless it's covered in a deep stack of sauerkraut and/or relish. (or if I'm not concerned about any traditional values but just personal taste, tomatoes or mango salsa or pineapple).
A quality hot dog on a warm bun with a tall stack of sauerkraut and a nice dash of brown mustard is OH SO SANDWICH.