Until we see how Broadway bounces back- including seeing if any of the current/new shows close, a new B'way house isn't going to be an attractive investment. While in recent years, all 41 were spoken for, that may not be the same for a while. Hopefully, things will bounce back quickly but too many unknowns for a new theatre (unless perhaps whoever is building in the lots next to the entrance put a theatre in the building for tax/zoning reasons). Before 42nd Street was fixed there were fewer theaters (34 I think) and some would still stay dark for years. Not saying that would happen again, but 41 may be a lot to fill for a bit (I'm ignoring the unavailability of the Cort and the Palace for the moment-by the time a new theatre was built they should be reopened).
Hopefully they will at least preserve the 45th Street facade and marquee. (46th street side is basically a plain wall- from the picture on Google Maps, there may have been decorative patterns in the brick at one point but they've worn away).