Yes, the hole erodes with each shot. How much exactly? How long will a factory BP last? IDK
For most folks, they will likely not wear out many BP's...they don't shoot that much. The factory plugs don't have a removable vent liner, so once the hole opens your option is to modify it, or buy a new plug.
RonLaughlin can take your factory plug and modify it to have a removable vent liner. He has done great work for many folks for quite a while.