Well this is why having humans in the loop is an advantage, so you get an Agreement in Principle to move the process forward.

Also, we're back to the fundamental problem which is that you can't use a house as collateral on the blockchain but you can in the real world.

There are also things like leveraged buyouts of companies which operate on a similar principle. The capital for the buyout is fronted by a bank loan secured against the company being bought.

And again, there's no timing issue because humans can understand there isn't really a sequencing issue and one party isn't going to just disappear with the funds halfway through the process, and everything is reversible through banking and / or the courts.