Phantom of London said: "Like it or not and dare I say it Stephen Sondheim is great but niche and needs big name for it to fly.
Looking at the past 4 Broadway productions, they all have something in common and that is they all played a large theatre (Shubert, Broadway, Winter Garden, Marquis, Imperial & St James) this may have affected the length of its run. When Imelda Staunton recently performed Rose in the West End it wasn't it a large theatre, but in a 1000 seat house and the production was all the better for it, it made the show more intimate and it worked. So would suggest going in one of the Broadway Playhouses, such as the Jocobs or Barrymore etc.
I would also have the artist portraying Rose just do it for 3 months, then another 'name' taking the role over, so what I am trying to say someone like Audra McDonald kick it off then someone like Sutton Foster, Kelli O'Hara etc take the role over, then when a new actress takes the role over it gets re-reviewed by the New York Times, you can get Patti Lupone and Bernadette Peters reprise their roles for 3 months. However would a known actress take over a role, if they cannot win a Tony?"
I have always been under the impression that it is dramatically cheaper to open a show in London than in NY. I do not know if 'dramatically' still applies, as it did in the past, but I do know that it is still a lot cheaper. Shows are also cheaper to run in London. So they have a lower upfront investment and a lower operating nut. That means that they can return their investment sooner. So, I really don't think the analogy works.
The other issue with a much revived show opening in a smaller theatre: premium pricing. Some shows that have opened in smaller theatres, e.g., BOM, DEH come to mind immediately, have been very expensive to see (because they could be) and had a lot of premium seats; this 'deadly combination for ticket purchasers' allowed them to achieve grosses one would typically associate with a bigger theatre. I just don't see another revival of Gypsy commanding those types of prices, which makes it almost impossible to return its investment.
Finally, I agree with your last point. I'd add one...how many famous people are going to be willing to take an iconic role with such a low bar for critical failure. And constant comparison to predecessors. I don't see it, and I am not sure how many people are up to the challenges of Rose, are right for it, and would sell tickets. (I have to say that I think Kelli O'Hara would be terrible as Rose).
There have been shows that have relied on replacement stars in the past; however, in most cases, continued success was rare. Even with the original production of Hello Dolly, I believe that -- were it not specifically for Pearl Bailey -- HD would have have had a much shorter run. Martha Raye, her predecessor, died at the box office, as did Phyllis Diller, her successor.
So, best to wait at least another 7 - 10 years to me.