I think the Westin is the southern-most property in the hi-rise district. According to some locals (and some construction supplies), the vacant lot just South of the Westin is ready for new construction, an addition to the Westin property.
Are you referring to the empty lot between the Westin and Divi Phoenix? We were staying at the Divi a few months back (which is where the boardwalk ends), and were just commenting on that lot and how long it will take before something goes in!
The parking lot area there by that station was improved on Westin's dime as a good will gesture with the upcoming construction. This was done in order to give locals especially, a place to enjoy the beach.