I'm sure you're correct, but I tend to look at this from the other direction. If money is the actual issue, why not take a step or two back from the (pretty much) full productions of shows that have become the norm over the last decade and go back to their roots and have singers in formal wear singing the scores and nothing more than a small set piece or two to suggest a setting?
Make them actual concerts again and even bring back the scripts in hand. I would think that would drive down the production costs and let them spend money where they should be spending it...on restoring scores. And lower costs would allow them to not have to try to schedule a blockbuster every season to support the more obscure titles.
People loved Encores! in the beginning just as much or more than they do now...I don't see any reason why downsizing the productions would drive audiences away.