Another possibility...
OK--suppose that Dred Scott goes forwards as historical. You can't loose your property just by crossing the line. But...one or more states passes another law, worded like the prohibition statutes. They specifically allow transportation of slaves through the state, provided the owner is simply transiting it. But staying there past a certain time and use is not allowed.
This is sufficiently different to go before a court again, perhaps all the way to the supreme court. The prohibition of alcohol could be used as a precedent, and a new court case comes forth. It might not be ASB for the court to rule in favor of state's rights, since the property owner's rights are given some protection. The state might even require registration of property under transit, so as to know when the limit is reached.
As for escaped slaves---well, it could be argued that they were not freed, since the owner didn't transport them there himself. (And if a slave escapes while already in a free state, I suspect that the slave might in fact be free...)
That sort of law could lead to an interesting series of compromises...or tension..either hastening or delaying the Civil War.