They probably will always be the biggest midland club. Unless there is a big shift, Albion, Blues and Wolves will always be 30 thousand clubs while Villa are a 40 thousand club.
If there was a big money benefactor who took one of the other 3 to a title win then things may change over time or if one of the 3 pulled off a marketing coup by pulling in more of an ethnic fanbase then again the gap could close but Villa are most likely to stay as the most "supported" team in the midlands.
Doesnt mean they are going to stay as the best
.