Well, I'm nervous about posting anything related to Sandy after the past few days on the forum, but here goes:
I think that it is inevitable that Sandy is going to grow and the best I can hope for is that they will do so in a better manner than seems to be their present course. Here is a little map I threw together of the area that is becoming Sandy's CBD:
The yellow line and purple box on the left are the Frontrunner tracks and anticipated station at 10200 S. The yellow line on the right is the current TRAX alignment and future extension to Draper beyond the current station at 10000 S.
The area in blue is the outline of the recent proscenium development. The areas in green are unused land.
I've added the red line as a streetcar to connect Frontrunner at 10200S to TRAX at 10000S via "downtown Sandy" and Southetowne mall.
I'm all for density, but why try and squeeze 3 large towers onto the small footprint in blue that is the current Proscenium proposal? One of the towers looks like it would have no access from any street whatsoever. I would rather see them spread towers to some of the other empty land in the area and allow other stuff to fill in between them naturally, creating a more viable, densified area.
Lastly, whether Proscenium and a theater happen in Sandy in any form, I think it unlikely that Sandy will ever trump DT SLC as the main regional center. The following map is of DT at the same scale as the map of Sandy at the beginning of my post. Compare the two and what each has to offer:
Downtown Salt Lake is going to continue to grow, and so is Sandy. Here's hoping that each will do so responsibly and that the two can somehow coexist.