So how in blazes does Madara expect Obito to sacrifice himself if Obito cannot experience the dream world itself when he is dead?
You'll notice that fratricide is very common amongst the Uchiha. It kind of goes without saying that one Uchiha's good idea involves at least one more Uchiha to act as a sacrifice.
Though to be fair... the original plan involved using Nagato for that purpose.
So, I really don't think Madara expects Obito to sacrifice himself. Though I imagine Madara also expected that Obito would not so blindly follow the original plan. ... Which may be part of Madara's plan in the end.
Or, perhaps the series will end with Madara/Obito destroying the world... only to find out they are in Itachi's Tsukuyomi; and everything has been an illusion.
Then we get to re-live the experience through the alternate world of Naruto depicted in Road to Ninja.
It's guaranteed to prolong Naruto's market viability for another 10 years!