Oh yes, "Leaked"
Keep in mind that dealers are the masters at turning anything into a profit...
I'm sure that the media and advertising will abound with tales of the great deals they're doing, but then when you get there you'll find the "massive savings" are off the list price, that nobody has been selling them at anyway. And then they'll tell you how they have no stock left, and will have to work extra hard to try and find you a car, and of course you have to sign today or you will miss out.
A lot of dealers are part of groups. If its a good yard and showrooms, it will simply be repurposed, and even at worts if the yard closes they'll just move their stock to another yard. Most of these groups are holding squillions in used-car stocks, so the last thing they want to do is crap all-over that.
I suspect the only way you will get a decent genuine savings is if Holden offers "cash back", otherwise any discount they offer on stock will be mostly snaffled by the dealers.
But, like anything, shop around.
If the best deal you can get on a similarly equipt i30 is $X, and you can get the Astra for $2k less, go for it.
Warranty wise, I imagine they will contract those out to another network. (When Saab went under, their warranty obligations were assigned to Holden.)
As for Parts, meh. If there is demand for parts, somebody will stock them. And worst case, hop on the interwebs and buy them from Europe.