The U-section would have been interesting, but it would have spaced the cars out so much before the straight it would have killed racing, rather like the extended bit in Bahrain (though I suppose this is only a problem for F1, but we are speaking about a hypothetical return).
Actually, I suspect that between the blind corners, the changes in camber and the changes in elevation, the U-section would have been very difficult. It would have been one of those corners where the driver can only drive at about 60%.
Wasn’t the the original point of Mateschitz buying it to use it as as a private test-track, but then testing was banned?
That was Alex Wurz’s plan. I think.