Yes the land bridges were intact long enough for the trek.
So they stayed intact long enough for the marsupials to make a journey of thousands of miles, with no food and then suddenly disappeared with no evidence of their existence after they made it safely to Australia?
There is a good hypothesis that at one time there was one land mass connecting all land.
And nowhere in that hypothesis does it mention that this land was connected anywhere close to 5,000 years ago.
What evidence are you specifically asking for
Any scrap of evidence that you could produce that shows how the continents could have possibly moved from a single land mass to their current positions in the time you advocate would do. Or how a planet that had been previously decimated by a yearlong flood could support the resources needed for the migration of thousands of animals to their current locations? Or how continents moving at the speed you propose wouldn't generate enough heat to boil every living thing on the face of the Earth? In fact I would be happy to finally read just one piece of evidence in support of creationism instead of just assertions.
'Qui non intelligit, aut taceat, aut discat'
The mind is like a parachute. It only works when it is open.-FZ
The industrial revolution, flipped a bitch on evolution.-NOFX
It takes all kinds to make a mess- Benjamin Hoff