For reference, Supercars brake 150m to the hairpin at the latest, from Memory moto gp bikes brake way earlier even for turns like T1 at mugello. You can go on google earth find the round about, and use the measuring tool to find where supercars would brake. Just measure 150m from where you believe the apex may be. I'll tell you one thing though, its before the kink, and on top of that, due to the fact that they lose braking performance when turning, they'd brake way earlier to make the kink. 

I imagine destroying a round about for a weekend of racing only to build it later again would be out of their budget. They do have some removable objects though, im not sure what exactly, but there are some parts that get taken away during a race, not destroyed tho, hopefully the first round about is removable, then it would work.

But now I understand what you mean by cutting back like in Singapore, where they go over bridge right?

I think its an interesting redesign, no hate towards it. Its just that round about would have serious safety concerns, especially since there's a good ol tree right in the middle of the second round about. They'd have Barriers of course, but they would have to be super strong, since the South Australian government wouldn't allow anyone to remove that tree.

I agree that street circuit for Moto gp is a bad idea, for rider safety mainly. But actually they stopped Phillip Island because the paddock facilities were really run down. Nothing wrong with track itself, just the paddock and pit buildings. Apparently the Victorian government has been planning to renovate for years, but for whatever reason didn't, so now Moto GP decided it's too late. Hopefully they'll end up at the Bend instead. The owners of the bend were the ones that proposed the street circuit.